Mold Bases

8/13/2019 Mold Bases

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Mold bases

Basic Molds are a class of molds that, while can be very basic in application, are molds

that have no Action incorporated into the mold to produce a part.

The parting line can be planer, non-uniform, angled, and may be complex.

Basic Mold Design

Before an n!ection Mold Design can be started the following criteria must be "nown, to

enable a proper design.

#art

$i%e

&unction Acceptable 'itness Mar"s for #arting (ine, Method of )!ection, and *ate

Material Type, and #rocessing +haracteristics, $hrin", Draft euirements

#roduction euired, Time &rame and (ife of Mold

Tolerance +onsiderations

unner

&inish $pecification, Data nserts

Machine

Type

noc" out Bar, $i%e and spacing

Tonnage #laten si%e

$hot si%e

(ocating ing hole si%e

/o%%le $pherical adius, and 010 Dimension

+oolant +onnector Type and $i%e

#rocessing +apacity $tudy

+ycle time

/umber of +avities euired #er Mold

#ossible Types of Mold bases

/umber of Molds to be 1rdered,

$pare +avity $teels euired

*eneral

'hat is the Timing of the Design2Mold Delivery3

f the above is "nown or specified, a mold design can be started.


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A GENERAL APPROACH MAY FOLLOW THE FOLLOWING STEPS:

(INJECTION MOLD DESIGN REQUIRES SYNTHESIS OF MANY

REQUIREMENTS AT THE SAME TIME )

$tart at the part and wor" your way out.

Determine the best gate location.+A) 4&low Analysis5 is a superior tool to help determine a proper gate location.

Determine the appropriate #ossible #arting (ines.

The location of an acceptable parting line will provide for proper e!ection of the part from

the mold.

A correct parting line will ensure that the part 0$tic"s0 to the e!ection 4core5 side of the

mold.

Determine a unner (ayout that suits the number of cavities needed for the mold andincorporate +old $lug 'ells into the layout.

The next three items need to be 06uggled7 at the same time. )!ection, +oolant lines, +avity steel

si%es.

Determine +avity steel si%es 4you should have and idea of cooling layout too, at this

point5. 'ill coolant holes be needed in the cavity steels3

Determine the )!ection method, and location of the e!ector contact area.

Determine +ooling (ine location per coolant line placement rules.

$elect a possible Mold base 4may change later5 that suits the design reuirements

4)!ection travel, coolant connectors counterbored, general si%e. Ma"e sure that the noc"-out

bars will actuate the e!ection system.

Determine te n!m"er #n$ %i&e ' S!'rt Pi**#r% nee$e$ 'r te m'*$+ E,ten$ te

E-e.t'r /#r i Ne.e%%#r0

Se*e.t # Sr!e /!%in12 #n$ L'.#tin1 Rin1 "#%e$ ' te M#.ine %e.iie$ 'r

r'$!.in1 #rt%+

L'.#tin1 Rin1

F!n.ti'n:

The function of a (ocating ing is to Align the Mold Base to the $tationary #laten side of

the #ress. The $prue Bushing is also located via a hole in the (ocating ing.

The (ocating ing is located and fastened into the Top +lamp #late 4T+#5 via

counterbored hole.


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T' C*#m P*#te (TCP)

F!n.ti'n:

The function of the T+# is to provide a means to attach the (ocating ring to the mold

base.

The T+# also provides counterbored holes for the $8+$0s that secure the A etainer

#late.

The T+# is located on the $tationary side of the press.


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A Ret#iner P*#te

F!n.ti'n:

The A etainer #late has many functions. The four drilled and counterbored holes are

machined for the *uide #ins which align the A side to the B side of the mold. A machined

opening is used to insert the +avity steels. &our tapped holes are used for the $+8$0s to hold the

T+# and related items to the A etainer #late. There is a milled slot on two sides of the plate to

provide for the placement of clamps that clamp the A side of the mold to the $tationary side of

the press. The hole in the center of the plate is for the $prue Bushing. There are four milledangle relief0s on the bottom called #ry $lots, this enables easy prying between the A and B plates

for opening the mold during maintenance or construction. There are also holes machined into

the sides for the provision of coolant.


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S!'rt P*#te (SP)

F!n.ti'n:

The $upport #late has many functions. The primary function of the $# to provide

support to the B side +avity $teels. #roper support will reduce the possibility of flash occurring

at the #arting (ine due to the B +avity steel 7bowing and flexing7 under the high pressures of

n!ecting Material into the +avity.

The location of the $upport #late is directly below the B +avity and etainer #lates, and

sets on top of the )!ector ails 2 8ousing.

There are typically several holes in this plate. They are machined for the following

components9 $prue #uller #in, )!ector #ins, eturn #ins, $8+$, Tubular Dowel, and the end of

the *uide 2 (eader #ins.


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C#3it0 Stee*%

F!n.ti'n:

The function of a +avity $teel is to provide the negative image of the desired part that

will appear on the A side of the mold above the parting line. 'hile not always the case, the+avity $teels MA: provide coolant lines for coolant. The +avity $teels contain the *ate, and

usually a small portion of the unner system.

The +avity $teels are located in a machined hole or poc"et, or may in fact be the entire

plate directly above the parting line on the A side of the mold. +avity steels typically are made

from 8;< or #=> Tool $teel.


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Sr!e /!%in1

F!n.ti'n:

The function of the $prue Bushing is to provide a seat at the spherical radius for the

/o%%le of the press. The $prue Bushing provides a 7path7 for the material from the no%%le to therunner system. The $prue Bushing is located via the (ocating ing, and the A etainer #late,

and touches the B side of the mold at the #arting (ine.


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Sr!e P!**er Pin

F!n.ti'n:

The function of the $prue #uller #in is to 7pull7 the material from the $prue Bushing at

the end of the Molding +ycle.

The location of the $prue #uller #in is directly Below the $prue Bushing, it is retained via

the )!ector etainer and )!ector #lates and passes through the $upport and B etainer #lates.

There are three typical $prue #uller #ins9 ;. 7?7 $hape, =. Ball,


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G!i$e$ E-e.t'r Pin #n$ /!%in1

F!n.ti'n:

The function of the *uided )!ector $ystem 4#in and Bushing5 is to ta"e the pressure off

the eturn #ins, )!ector #ins and the $prue #uller #ins. f the mold is set to run with the )!ectorsystem actuation in the hori%ontal position 4typical5, the e!ector sub assembly is cantilevered, and

thus will put stress on the return, sprue and e!ector pins. The *uided )!ector $ystem will reduce

if not eliminate these stresses.

The *uide bushing is located between the )!ector and )!ector etainer #lates, and the

*uide #in is placed either in either9 ;. The bottom of the )!ector 8ousing, or =. n the $upport

#late. n either case the #in resides in the open space of the e!ector housing.


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C#3it0 Stee*% (/ Si$e ' M'*$)

F!n.ti'n:

The +avity $teels on the B side of the mold are identical in function to the A side cavity

steels, with one additional function, they typically have holes for )!ector #ins.

The B side +avity $teels are located directly below the A side cavity steels, on the B side

of the #arting (ine.


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G!i$e /!%in1

F!n.ti'n:

The function of the *uide Bushing is to provide alignment of the two halves of the mold

via the *uide #in. f the bushing is steel it is hardened and ground.

The *uide Bushing is press fit into the B etainer #late.


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E-e.t'r Pin

F!n.ti'n:

The function of the )!ector #in is to e!ect the part from the mold at the end of the molding

cycle. )!ector #ins always form a portion of the part and2or runner.

The number of )!ector #ins in a mold varies depending on part and unner geometry.

The #in is retained via the )!ector and )!ector etainer #lates and pass through the $upport and

B etainer #lates.

G!i$e (Le#$er) Pin


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F!n.ti'n:

The &unction of the *uide #in is align both halves of the mold at the #arting (ine. The

*uide #in aligns with the *uide Bushing.

The *uide #in is hardened and ground, and is press fit into the A etainer #late. TheTop +lamp #late provides a bac"er plate for the top of the pin.

/ Ret#iner P*#te


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F!n.ti'n:

The &unction of the B etainer #late is to retain the B side +avity $teels, and many

times, has a portion of the unner machined into the plate.

The B etainer #late is located directly above the $upport #late, the top of the plate isusually referred to as the #arting (ine. 8oles are machine into this plate for the following

components9 *uide Bushings and eturn #ins.

E-e.t'r P*#te


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F!n.ti'n:

The )!ector #late provides a bac"er plate for retaining the )!ector, eturn, and $prue

#ins. The underside of the )!ector #late is where the noc"out ods from the #ress touch, and

ma"e the )!ector sub assembly move to e!ect the part4s5.

The )!ector #late rests on the $top #ins, and has counterbored holes for the *uided

)!ector Bushings, and clearance holes for the $upport #illars. The )!ector #late is fastened to

the )!ector etainer #late via $8+$0s.


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E-e.t'r H'!%in1

F!n.ti'n:

The )!ector 8ousing has many functions. #roviding room for the )!ector #ins, )!ector

#late, )!ector etainer #late and $prue #uller #in to move during the )!ection #hase of the

molding cycle is the foremost function of this component. The )!ector 8ousing also provides

for +lamping $lots to fasten the B side of the mold to the Movable #laten of the press.

The )!ector 8ousing can come in two configurations. ;. Three steels 4Two ails and one

Bottom +lamp #late5 fastened together, or =. n a single welded or machined casting. 8oles aremachined into the )!ector 8ousing for the following components9 $8+$ for holding the B side

together, $8+$ for $upport #illars, Tubular Dowel, $top Buttons, *uided )!ector 4(eader5 #ins,

and noc"out 8oles for the noc"out ods on the press.


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E-e.t'r Ret#iner P*#te

F!n.ti'n:

The function of the )!ector etainer #late is to retain the )!ector #ins, $prue #uller #ins,*uided )!ector Bushing and the eturn #ins to the )!ector #late. There are drilled and

counterbored holes for each of the components mentioned above.

The )!ector etainer #late is fastened to the )!ector #late with $8+$0s. There are also

clearance holes for the $upport #illars.


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SHCS (S'.4et He#$ C# S.re5)

F!n.ti'n:

The &unction of the $8+$ in a mold are to hold the various plates in mold together.

There are several $8+$0s in a typical Mold. There are $+8$0s that hold the )!ector

8ousing, $upport #late and the B etainer #late together, two $8+$0s pass through the Tubular

Dowels. $8+$0s also hold the Top +lamp #late and the A etainer #lates together. $8+$0s also

hold the (ocating ing to the Top +lamp #late.

Ret!rn Pin

F!n.ti'n:

The function of a eturn #in is to return the entire )!ector $ub assembly to the home

position. f eturn #ins were not utili%ed, the e!ector sub assembly would be returned via

)!ector #ins, this is not acceptable, as it would damage the end of the e!ector pins and would

alter the appearance the part.

The eturn #in is retained between the )!ector and the )!ector etainer #lates. Theeturn #in reuires holes in the $upport #late and the B etainer plates.


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T!"!*#r D'5e*

F!n.ti'n:

The &unction of the Tubular Dowel is to provide proper alignment between the )!ector

8ousing, the $upport #late, and the B etainer #lates.

There are two Tubular Dowels and they are lightly press fit into the B etainer and

)!ector 8ousing. A $8+$ passes through the hole in the dowel.


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St' /!tt'n ('r Pin)

F!n.ti'n:

The function of the $top Button is to provide a minimal contact area between the )!ector

8ousing and the bottom of the )!ector #late. The space provides an area for debris in molds that

are set in the vertical direction.

The $top Button is press fit into either9 ;. The )!ector 8ousing or =. The bottom of the

)!ector #late.


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#lan view of core

#lan view of cavity


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$ecction A-A

$ecction B-B


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Detail of gate

B1M

Titlebloc"


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unners

A unner is a machined groove located between the $prue Bushing and the *ate.

The function of a runner is to provide a passage for the material to flow from the $prue

Bushing to the *ate.

There are many types of unner cross sectional shapes. Most common shapes are the

&ull ound, 8alf ound, and the Trape%oidal.

As the unner branches and changes direction from the $prue to the *ate the runner is

reduced in its cross-sectional area 4typically about =@5. The portion coming from the $prue is

referred to as the #rimary unner, the next section is referred to as the $econdary unner, and

followed by the Tertiary unner.

The length of a runner system should be "ept to a minimum. n!ection #ressure build-up

due to long runner lengths can be reduced by increasing the runner diameter. 8owever, larger

runner diameters increase cycle time due to the added volume of material that needs to be

chilled2solidified.

R!nner t0e%

The most efficient unner shape is the &ull ound, followed by the Trape%oidal and

followed by the 8alf ound unner shape. There are many modified versions of these runners.

F!** R'!n$


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H#* R'!n$

The 8alf ound runner is simply a runner system machined with a ball nose cutter into

one plate of the mold.

Tr#e&'i$#*

Trape%oidal unners are very common in three plate molds. 'hile not as efficient in

chilling effect of a full round runner, the ease of cutting the runner shape, and the elimination of

the need to mate two runner plates together, ma"es the trape%oidal runner a good second choice

of runner shape.

R!nner $i#meter%

unner Diameter si%ing is directly related to the wall thic"ness of the part. Typically

standard cutter si%es are utili%ed to machine the runner system, select the closest standard cutter

si%e to "eep regrind levels below =@.

The runner that feeds material to the gate and part cavity should be ;.@ times the wall

thic"ness for semi crystalline materials. &or Amorphous materials add approximately >. &or

each branch of the runner towards the $prue add .>=@ 4/5. The 1 dimension of the $prue

should then be .>@> larger than the main runner. The no%%le DA should then be .>=@ less thanthe 1 Dimension.


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*eneral thermoplastic materials with no fillers, and their typical runner diameters.

Material Diameter Material Diameter

AB$, $A/ .;C@ - .


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F'!r C#3it0 L#0'!t (N' C'*$ S*!1 We**)

Si, C#3it0 L#0'!t


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Ei1t C#3it0 L#0'!t

C'*$ S*!1 We**

+old $lug 'ells are highly desirable in an n!ection Mold. The +old $lug 'ell provides

a small reservoir 4well5 to trap air, and impurities before they enter the unner, *ate and

+avity.

A +old $lug 'ell is located above the $prue #uller #in. Typically, as the runner changes

from a primary to secondary, and, secondary to tertiary there is also a cold slug well at each

intersection.

R!nner Are#%

1f primary concern for an effective runner system is the Folume to $urface ratio.

Minimi%ing the surface area of the runner reduces the cycle time and pressure drop.

)uivalent 8ydraulic unner Diameter calculations can be performed to compare various

runner cross sectional shapes. 8ydraulic Diameter 48d5 is an index of the resistance of flow, The

higher the 8d the lower the resistance to flow.


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The formula9 A 2# G 8d

where9 A G cross sectional area

# G perimeter

8d G 8ydraulic Diameter

C'*$ Sr!e

A standard +old $prue Bushing provides a means for the material to travel from the

Machine /o%%le to the unners.

The /o%%le end of the bushing has two important dimensions. 1ne is the hole opening, it

is referred to as the 717 dimension, and the other is the spherical radius that seats with the

no%%le. The 010 dimension should be 2 or .@E T#&. The taper hole diameterat the unner end of the bushing should be eual to, or be slightly larger than the runner

diameter. A radius of approx. .>E should be placed at the taper and runner intersection.

Below the $prue Bushing should be a provision for a $prue #uller mechanism. There are

three common types of $prue #ullers, and they are typically .=@ below the parting line, which

functions as a cold slug well.

everse taper well

0?0 cut on $prue #uller #in

Bulb machined on the end of the $prue #uller #in.

*ussets are sometimes cut into the $prue Bushing to help reduce the cycle time.

H't r!nner

A 8ot unner Mold is similar to a hot glue gun. Material is heated to a molten state, then

it is dispensed at the tip to the desired area. #arts can be small single gated, or large and multi-

gated. 8ot unner Molds have many uniue advantages over 7+old unner7 molds.

'hile 8ot unner Molds are typically more expensive than 7+old unner7 molds, the

cost of the mold can be offset in other ways. Thermoplastic 8ot unner Molds can reduce costsdue to9

No scraping of the runner. As the term implies, the runner in a 8ot unner mold stays

in a molten state at all times 4no regrind5.

Reducing the cycle time. n a +old unner mold the runner typically has the largest cross

sectional area, therefore, the runner ta"es longer to solidify. )liminating the runner

reduces the overall cycle time. &urthermore, in!ection time is reduced due to the shot si%e

being reduced by the elimination of the runner.

8ot unner Molds have the ability to improve both part and mold design with flexibilityof gating locations, which provides options for cavity orientation. #ressure drops are greatly


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reduced due to the balanced melt flow as the temperature is consistent from the machine no%%le

to the gate.

#recise material temperature control is critical to successful 8ot unner processing.

G#te%

A *ate is a small area between the runner and the part cavity. The type, si%e and location

of a *ate in an in!ection mold is critical to efficiently producing uality parts.

The type of gate selected depends on many factors including9 *ate witness mar"s,

Material Type, &iller used 4if any5, Tooling +osts, $crap Allowance, and the Mold #lates used

among others.

A single gate per cavity is desired, however, part si%e and the material used may reuire

multiple gates to be used.

(ocate the gate in an inconspicuous location of the part if possible. The *ate location

should be at the thic"est wall of the part 4flow from thic",to thin5 and the thic"ness of the gate

should be approximately two thirds the si%e of the wall.

The gate location and the surrounding area is also the highest area of stress in the final

part. Do not position the gate at a location that part function indicates bending or impact

strength is reuired.

There are two general categories of gates9

;. Automatic De-gating

Automatic de-gating includes $ub gates and > of the wall thic"ness up to .;=@ in. The width should eual = times the

depth. as it would appear in a mold.

An )dge *ate will leave a $car eual to the cross section of the si%e of the gate.


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F#n G#te

A &an *ate will leave a $car the si%e of the cross section of the gate.

Pin G#te

#in *ates are used in three-plate molds. The actual get diameter is from .> - .;>>diameter.


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A #in *ate will leave a small $car that is the si%e of the gate.

Rin1 G#te

A ing *ate will produce a $car around the entire part, the height is eual to the gate

height.


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Sr!e G#te

The $prue gate is used when cylindrical parts need to be balanced and concentric and2or

have very good weld-line strength.

A $prue *ate will leave a significant $car eual to the si%e of the sprue diameter at the

point of contact of the part.

S!" G#te- May Also called a Tunnel *ate, +ashew or Banana

The diameter at the gate is .>-.>H> for unfilled materials and .;>>-.;=@ for filledmaterials. The angle is typically at degrees from vertical. )!ector #ins are reuires to ensure

automatic de-gating.


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A $ub *ate will leave a #in si%ed $car on the part.

T#" G#te

A Tab or &ilm gate typically is used where part reuirements are for flat and2or very

minimal warpage. The Tab reuires post processing to remove the scar.

C''*in1

+onsidered the third phase of the n!ection Molding +ycle, the +ooling #hase consumesthe greatest amount of time. Therefore, it is a serious area for designers and mold ma"ers to

ma"e sure that all +oolant schemes have been thoroughly investigated for their suitability.

+orrect cooling of an n!ection Mold is reuired to produce good uality parts at an

optimum rate. All n!ection Molds have some sort of cooling provision to ensure efficient part

production. +hilled water 4C>-;> degrees &5 is perhaps the most common medium to extract

heat energy from the the mold. +oolant lines are drilled into various plates at specific locations

to provide even uniform cooling of the mold cavity steels.

Many standard cooling components are available to provide the Mold Designer with

many options to achieve the uniform cooling patterns needed for ensure uality part production.The most common coolant line diameter is 2;E, while @2;E and H2;E are used less freuently.


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+ooling rules

+oolant lines will be9

.


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/#*e%

C'er A**'0 Pin%


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Term#* Pin%

/!""*er T!"e%

C#%.#$e 5#ter -!n.ti'n


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W#ter m#ni'*$

E-e.ti'n

+onsidered the fourth phase of the n!ection Molding #rocess, )!ection is the process of

removing the solidified part from the mold. +ommon e!ection methods include9 )!ector #ins,

)!ector $leeves, )!ector Blades and $tripper #late.

)!ector #ins and Blades and to a lesser extent the $tripper #late and )!ector $leeves, all

leave a 7witness mar"7 on the finished part. &urthermore, the e!ector pin and blade will either

;5 leave an impression or =5 a protrusion, where the pin or blade is located on the part.

(ocating e!ectors is important. Balanced pressure on the part by all e!ectors is important.

Accurate location of e!ectors on part walls, ribs, and bosses is highly desirable. #art appearance

and function must be ta"en into consideration when designing the e!ection system. $tripper #late

e!ection is highly preferred due to the even pressure and minimal witness mar"s on the part.

The number and si%e of e!ectors used is dependant on the si%e and shape of the part. Draw

#olishing is recommended for thin walls, ribs, or minimal draft areas.


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)!ector #ins are sometimes used to help e!ect the runner system from the mold. f a $ub-

*ate is used in the mold, an )!ector #in is used near the beginning of the drop of the gate to help

brea" the part from the runner2sub-gate. Accelerated e!ector systems are sometimes needed to

e!ect the part from a tall core. t is also possible to 7Tip7 a part to get the part to fall from the

mold in a certain direction.

T0e% ' e-e.t'r%

)!ector #ins are available in a wide variety of si%es and materials.

E-e.t'r S*ee3e

An )!ector $leeve is basically an )!ector #in with a hole thru the center. The hole is

used for a +ore #in to form a portion of the desired part. The +ore #in touches the part, the other

end of the +ore #in runs thru the )!ector 8ousing and terminate near the bottom of the

moldbase. The actuation of an )!ector $leeve is li"e an )!ector #in.

E-e.t'r /*#$e%

)!ector Blades are available in a wide variety of si%es and material types. )!ector Blades

can be used in area that have a 0$lot0 for the blade whereas an e!ector pin would only be able to

touch a smaller portion of the part.

Jie06Je.t'r

A 6iffey-6ector is a standard part that aids in the e!ection using.

Strier P*#te%

$tripper #lates are used to strip the part off the +ore $teel. The $tripper #late is actuated

via $tripper Bolts from the A side of the mold, or by the )!ector Mechanisms in a variety of

ways.

Air P'et%

Air #oppets are standard components that aid the e!ection of a part by using compressed

air within the mold. The timing of the actuation of the air is controlled by the controller of the

press, the amount and the pressure is predetermined during mold tryout.

A.ti'n m'*$%

Action molds are molds that have some sort of mechanical 0Action0 incorporated into the

design to enable molding of complex part geometry. Any significant hole, slot, undercut, or

thread that is not perpendicular to the #arting (ine reuires Action to enable the mold to produce

the part.

S*i$e A.ti'n

$lide Action reuires several mechanical components to enable the molding of complexpart geometry.


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$lide Action molds typically contain the following components9

Angle2+am28orn #in

$lide

(-*ibs

'ear #late$lide etainer

$lide (oc"

/ote9 The (-*ib should /1T move with the slide.

S*i$e #n$ Liter

The image below is a section thru a $lide and (ifter Action Mold.

Liter m'*$

(ifter Action in an in!ection mold provides for the molding of undercuts, lips and other

similar geometry on parts, and also aids the e!ection process.

Typical components in a lifter mold include9

(ifter

T-+oupling

I-+oupling

The Animation of the (ifter Mold below can be repeated by refreshing this page.

E#r*0 ret!rn %0%tem

'hen a slide cavity steel occupies the same space of an eventual e!ector pin, there is aneed for an early return system in the mold.


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f an early return system is not designed into a mold with the circumstances above, the

slide will attempt to return to the closed position, before the e!ector pin is returned, and will

cause a collision.

H0$r#!*i. A.ti'n

8ydraulic Action in an n!ection Mold, usually means that a hydraulic cylinder has been

incorporated into the design to enable a component 4core pin, cavity steel, etc5 to be moved at

some phase during the in!ection molding cycle.

Typical components for 8ydraulic Action are9

The 8ydraulic +ylinder

Mounting Brac"et, and relater connectors

The timing control of the actuation of the 8ydraulic cylinder is typically done via

)lectrical2Mechanical switches attached to the mold base, or, more commonly directly attachedto the controller of the press.

C'**#%i"*e C're

+ollapsible +ore molds provide a method to produce under cut 0(ips or Threads7 in an

in!ection molded part.

$tandard collapsible cores can be purchased with altering of the portion that forms a

portion of the part. f a standard collapsible core will not wor" in a particular design it is usually

possible to design one to meet the design reuirement.

Ge#rin1

*earing with an in!ection mold to produce full threads is common. There are many

considerations 4#art, #ress, $i%e of Mold base, /umber of cavities, etcJ5 that have to be

considered to produce the pasts to specification.

H't R!nner M'*$

A 8ot unner Mold is similar to a hot glue gun. Material heated to a molten state, then

it is dispensed at the tip to the desired area. 8ot unner Molds have many uniue advantages

over 7+old unner7 molds.

'hile 8ot unner Molds are typically more expensive than a 7+old unner7 molds, the

cost of the mold can be offset in other ways. Thermoplastic 8ot unner Molds can reduce costs

by the following9

No scraping of the runner. As the term implies, the runner in a 8ot unner mold stays

in a molten state at all times.

Reducing the cycle time. n a +old unner mold the runner typically has the largest cross

sectional area, therefore, the runner ta"es longer to solidify. )liminating the runner

reduces the overall cycle time. &urthermore, in!ection time is reduced due to the shot si%ebeing reduced by the elimination of the runner.


45/80

8ot unner Molds have the ability to improve both part and mold design with flexibility

of gating locations, which provides options for cavity orientation. #ressure drops are greatly

reduced due to the balanced melt flow as the temperature is consistent from the no%%le to the

gate.

7ie5 ' .#3it0

7ie5 ' e-e.t'r


46/80

Se.ti'n /6/

Se.ti'n A6A


47/80

In-e.ti'n M'*$in1 Pr'.e%%

The n!ection Molding #rocess in its simplest form is9

The process of ta"ing plastic at room temperature, heating it to a fluid state, forcing the

material into a cavity that is the negative shape of the desired product, allowing the material to

solidify, then remove the part from the mold.

A more technical description of the n!ection Molding #rocess is9

#lacing material in the hopper of the n!ection Molding press, 8eating the material in the

barrel via band heaters and friction to a fluid state, forcing the material through the /o%%le,

entering the $prue Bushing, then entering the unner system and *ate, the material then enters

the +avity which is a negative image of the desired part, the material is held under pressure whileit solidifies, then the part, gate and unner are )!ected from the mold.

M'*$in1 m#.ine

The function of an n!ection Molding Machine is to convert pelleti%ed or granular plastic

material into a part.

n!ection Molding Machines are typically referred to by their si%e. +lamping tonnage and

$hot si%e 4o%.5.

In-e.ti'n M'*$in1 M#.ine


48/80

C''*#nt M#ni'*$ #n$ C'nne.t'r%

S*e$


49/80

N'&&*e #n$ /#n$ He#ter%

P*#ten% #n$ C*#m S*'t%


50/80

St#ti'n#r0 P*#ten #n$ L'.#tin1 Rin1 H'*e

E*e.tr'ni. C'ntr'* P#ne*


51/80

M'3#"*e P*#ten #n$ 8n'.4 '!t /#r H'*e%


52/80

#roper Fenting in an n!ection Mold is critical to producing uality parts. The si%e,

location, and amount of Fenting reuired for proper molding, varies with part geometry and the

material used. &low analysis can be used to predict approximate venting locations. Typically the

mold ma"er during mold tryout, will develop the vents.

#roper Fenting will eliminate short shots and burn mar"s on parts due to trapped gassesnot being vented properly. Fenting will also provide for even flow of the material.

Cin.i 9;

M#teri#*

n!ection molding raw material typically arrives at a processing facility in a pelleti%edform.


53/80

Materials for n!ection Molding come in a wide variety of types for thousands of different

applications. Materials can be custom blended for a particular application.

Material arrives to a molding production facility via one of three ma!or methods9

; *" /#1%


54/80

G#0*'r$ (Ar',


55/80

C'n$!.ti3e Fi**er%

)lectrical and Thermal conductivity can be enhanced by adding9

Aluminum #owders, *raphite, +arbon &ibers

Rein'r.ement Fi"er%

An increase in Tensile $trength, &lexural Modulus, and 8eat-Deflection Temperature, as wellas reducing $hrin"age and 'arpage can be attained by adding9

evlar, *lass, Baron, +arbon, and &ibrous Minerals

CAE i** #n#*0%i%

+omputeri%ed Mold &illing Analysis9

1ptimal &low of material thought the Mold +ycle, can be predicted with a high degree of

accuracy using +omputeri%ed Mold &illing Analysis. The analysis can also aid in the balancingof family molds so that pressure, temperature, and time of the fill are balanced before tryout.

Fi** time

Air tr#%


56/80

Pre%%!re $r'

G*#%% m'$e*


57/80

In-e.ti'n re%%!re


58/80

P*#%ti. *'5

We*$ *ine%


59/80

F*'5 Fr'nt Temer#t!re

T''* %tee*%

The proper selection of the type of Tool $teels used to form the part cavity is an

important consideration to successful n!ection Molding.

Farious alloys are available to meet the performance needs of the mold. +ertain molds

may need wear resistance, and, high hardness at the #arting (ine. 1ther molds may reuire

higher toughness to reduce mechanical failure.

The give and ta"e of the desired properties is a constant concern with the selection ofmolding materials. f high hardness and wear is needed for the cavity steel, the brittleness

becomes a factor. f toughness is reuired of the cavity steels, a reduction of resistance becomes

a factor, especially when molding mineral and glass fibers.

P69;

#-=> Tool $teel is perhaps the best overall steel for forming a cavity in an n!ection Mold.

Advantages of using #-=> Tool $teel include9

)asy to machineK

$upplied in a pre-hardened state at c -


60/80

(arge si%es are minimal ris"s during heat treat

+an be used for abrasive materials, for short runs.

Disadvantages of #-=> include9

/o moving of mating steels of #-=> as galling will occur, 8-;< is a

suitable alternative steel for this application.

H6-@=

mechanical fatigue resistance is reduced, compared to other higher hardness steels.

Advantages of 8-;< include9

Toughness

Disadvantages of 8-;< include9

(ow hardness 4relative to $-5

S6>

$- is similar to 8-;


61/80

/ic"el plating

Ma"ing the mold cavities from $tainless $teel

A*tern#ti3e Pr'.e%%e%

C'6in-e.ti'n


62/80

F!%i"*e C're

G#%6A%%i%te$


63/80

L'56Pre%%!re

P!%6P!**

C'mre%%i'n


64/80

Str!.t!r#* F'#m

L#me**#r

Li3e6Fee$


65/80


66/80

Mold Design Cutting-Plane Line Determination

and

Section View Representation

1b!ective9 To show as clearly as possible the entire inside of the mold.

C!ttin1 P*#ne Line:

#lace the +utting plane line so that it cuts through the part, gate, and runner sprue, sprue

puller.

Then add to the cutting plane line to include e!ector pins and core pins 4if used5.

/ext you should include the coolant features and the support pillars.

Then add as many standard Mold base components as possible.

emember9 :ou must include at least one representation of every component in the

section view4s5, it may be cut through 4preferred5 or it may appear as a hidden feature.

L'.#tin1 Rin1

$how the locating ring cut in one view, and a solid in the other view regardless if the

cutting plane line passed through it or not.

Line% "e0'n$ te .!ttin1 *#ne *ine

$how all solid lines beyond the cutting plane line 4)!ector pins, support pillars etc.5 Thisincludes above and below the e!ector plates.

Hi$$en *ine% in %e.ti'n 3ie5%

Do not show any hidden lines that would duplicate any other feature.

F#%tener%

#lace two small $0 s of the end of the fastener about one dia. into the tapped portion.$how no threads in the untapped portion.

Center*ine%

Be sure to include all centerlines of all features.


67/80

C!ttin16*#ne Line Dre%%6!

1ptional on the cutting-plane, you may place thin lines on the outside corner of the

cutting-plane as the cutting-plane ma"es a right angle cut.

Se.ti'n Linin1

f you cut thru a $1(D cylindrical ob!ect, D1 /1T section line this itemL Ise double

lines for Tool $teels.

Note:

'hile not a standard 4A/$, $1, M( etc.5 :ou may use a thin line with two $0s in the sectional

view to represent the right angle cut of the cutting-plane line.

PLEASE???

$tudy these simple rules, Try to apply them 1/ :1I 1'/, and as" uestions if you

do not understand anything about them.

De%i1n %t#n$#r$%

Dowels: Ise .;= increments on the dia. (engths must be standard. /1 blind dowel holes. 1nrare occasions relieved dowels can be used. )ffective length on dowel is = times the dia

engagement per steel.

Fasteners:Ise only .;= increments on dia. $eldom will you use less than .


68/80

St#m:#lace a general note9

$tamp9 &erris $tate Iniversity

+AD Drafting Tool Design

Tool Q MMDD::-MR 4Month Date:ear-start with M>;5

#art /umber is the same as Tool /umber except replace M with a #

Cutting Plane Line:will be #hantom 4see handout on determination5.!ic"ness:.>@> Thic" for plotter, .>;< Thic" for printer. Ise proper setup in +AD for

both plotting and printing.

Section #D$s:4AA, BB etc.5 are placed in bac" of the arrows and are .


69/80

in the stoc" list 4see example5. All carbon steels will be specified as +-;>;C, +-;;(;, +-;>@,

or +-;>E>, D1 /1T use +$, +&$.

Position of detail:f details are shown out of position it must be noted on the leader line, and or

on the detail itself.

Center line:#lace centerlines on A(( appropriate features, this is reuiredL.

e%t:

All &onts )xcept $ection D and #lan Fiew (abels, on layout shall be9

omans with an 1bliue setting of ;@.

/otes Text 8eight is .;C.

Bill of Materials and Title bloc" 4ddedit but, be sure to change the font5.

$ectioning 4$ee $ectioning28atchine5.

$toc" list examples9

@ C $TD .=@> DA R ;.@> D'(

;> $TD .> $8+$A(T)U)R-HM-E < = #I DM) )6)+T1 #/ ;

= ; 8 ;< ;.>>> R =.>>> R


70/80

UU 4name and address of vendor two5

/ote9

$tandard in our shop will be9

A(( fasteners 4$8+$, and $tripper Bolts5 washers, and nuts.

'hen ordering $teels, place the material type is the Material +olumn

Ise /1 &ractions in the B-1-M

Ce.4*i%t /e're T!rnin1 in # P*'tte$ De%i1n

(9; tin1% t#t ee.t 0'!r 1r#$e)

Note9 This is a guide that when applied in a serious manner, will provide for eliminating

errors that you should have "nown either before this class or have been given information as to

the reuirement, it is n'tintended to cover all drafting and design reuirements.

Line%:

;. +enterlines placed on all features that reuire them.

=. +utting #lane (ine is .>@> thic" when plotted.


71/80

/#**''n #n$ St'.4 Li%t

;@. Balloons are . Dia. and placed in a logical order.

;E. (eaders are curved and pointing to the edge of the detail.

Mi%.+

;. $ection views are correct per +utting #lane $ectioning $election handout.

;C. Machine /ame and $i%e are placed in 1 holes.

;H. +ounter drilled holes are correct for )6, $prue, and others features.

=>. All Threads are correct per lecture.

P*'ttin1

Y'! m!%t !%e m0 /'r$er #n$ Tit*e"*'.4 'r #** *'t%

DO NOT scale my Titlebloc" to fit your drawingLJ nstead9 file your drawing for

bac"up. Then scale your drawing to fit my Titlebloc". And save it under a new name.

All #lots M!%tbe plotted to stated scale 4/1 scale to fit plots5

Minimum plotting color reuirements9

$olid fill color red of part, gate, runner, sprue sections 4edge of steel will be blac"5.

+oolant lines cyan

+utting plane ed

All +enterlines are to be ed

All others entities blac"

1ptional #lotting

1ption of using your color scheme upon approval


72/80

/ote9 /1 plotting of any yellow lines at anytime L

Design review9

Mar" 8ill

D)$*/ D)#ATM)/T +8)+ ($T

#art /ame9WWWWWWWWWWW Tool QWWWWWWWWWWWWWWWMetric2)nglish

#art &ile /ame9WWWWWWWWWWW Tool &ile /ame9WWWWWWWWWWWWMetric2)nglish

A+ PART DATA B LINE UP INFO C4$

>;. 8as the !ob folder been +reated3

>=. 8ave part edits been reviewed3

>C. 8as the part been completely reviewed for molding3

>H. s part data complete3 $M X 1$M3

;>. Are part changes reuired3 f so, are s"etches attached3

;;. Do all ribs have adeuate draft3

;=. Are ribs too thic" at the base3 4> - @> Max.53

;.@on 1.D. X .D.5 3

; 'hat is the shrin" factor3

;@. Are parts identical3 Mirrored or rotated3

/+ RUNOFF C4$

>;. 8as the parting line been completely defined3

>=. s relief shown3

>


73/80

C+ GATING C4$

>;. 8ave gate and drop locations been supplied or determined3

>=. Are gates balanced and shown complete3

>. Are gates shown in a R si%e view3

>@. s a manifold or sprue reuired3

>E. Are cashew inserts and screws designed if reuired3

D+ MOLD SIE C4$

>;. Does mold fit into customerPs press3

>=. Do parts clear tie bars3

>. Are stac" up dimensions and high point shown with overall bloc" si%es called out3

>@. s S1 corner shown3

>E. Does mold fit min. and max. shut height3

>. s top of mold and operatorPs side called out3

>C. 'ill design function in press3

>H. Are eyebolts 2 clamp slots shown3

;>. )yebolts to correct si%e3

;;. )yebolt sheets filled out3

;=. )yebolts designed in all loose pieces weighing in excess of > pounds3;,> been set to +( of +ore3

E+ Liter%C4$

>;. 8ow many lifters3

>=. Do lifters travel without any interference3

>. Are lifter rod pinning reuirements on bloc"-up sheets for straight up lifters3

;;. Are rib cuts reuired and complete3

;=. 8ave designs been compared for lifter material3

F+ SLIDES CORE PULLSC4$

>;. 8ow many slides3


74/80

>=. Do slides have sufficient room to travel in slide poc"et3

>. Are slide wear plate poc"ets surfaced3

>@. Are all fillets correct si%e3

>E. Are the layers all correct3

>. Are all slides written out individually, labeled, and named properly3>C. Do slides and labels match design file3

>H. s edm reuired3

;>. Are bloc"-ups complete with si%es and setups3

;;. Are core-pull bloc"-ups reuired and complete3

;=. Are screw locations reuired and incorporated into surface file3

;;. 8ow many inserts3

>=. Are inserts burned or cut3

>. Are screw locations reuired and incorporated into surface file3

;;. Are rib cuts reuired and complete3

;=. 8ave designs been compared for insert material3

H+ SLEE7ESC4$

>;. Are sleeves reuired3

>=. 8ow many3 Are spares reuired3

>. Are carrier2extensions reuired to "eep standard length3

>@. 8as the sleeve been designed to achieve between.@-= ream on D3 Z for the 1D3

>E. 8ave the sleeves been labeled and sections cut through all of them3


75/80

>. Do the sections have depths of part from core surface and the D and 1D

dimensioned3

>C. Are sleeve assemblies ready to fabricate3

>H. f special si%e sleeves are reuired, are they ordered3

I+ CORE PINS (/LIND THROUGH) C4$

>;. Are pins blind 4press fit from the front5, or through4stationary core pin from the bac"53

>=. f pin are through pins, are they "eyed3

>. 'hat is the purpose3>@. Are pins shown complete3

>E. Are pins dimensioned at part area to show depths, [, and draft3

>. Are pins labeled in #lanviews X $ections3

J+ CORE PULLSC4$

>;. Are core pulls reuired3

>=. 8ydraulic or mechanical3

>. Are sections cut through all core pulls 4and labeled53>@. f hydraulic, is design complete9

a. s cylinder mounting shown3

b. s standard pin carrier used3

c. 8ave cylinder orders been written, chec"ed, and given to purchasing3

d. s pin carrier "eyed and retained3

>E. s pin carrier spring loaded3

>. s part feature formed by pin dimensioned with tolerance3

>C. Are core pull assemblies ready to fabricate3

8+ WATER SPECIFICATIONS AND

REQUIREMENTS

C4$

>;. 8ave the customerPs specs been reviewed3 ncorporated3

(ine Y \ \ Bubbler si%e [ 4$tandard std. ; si%e larger than water line [5

&itting type 4Main connections5 \ +ounterbores \

+ircuit layout 4i.e. flood, forced5 \ Manifold or Falves \ 8ose color or type


76/80

L+ WATER DESIGNSC4$

>;. Are sections cut through all lines and labeled R or : value3

>=. Are any coolant lines taped into core steels3

>. Do all sections match #( labels3

>@. Are all inPs, outPs, and loops labeled3

>E. Are flow arrows or layout sheets reuired to help follow flow4i.e. complex bumper53

>. 'ater line spacing suitable for part and mold si%e3

$mall =-


77/80

>. Are rest buttons located directly next to hydraulic cylinders3

>@. Are limit switches shown X protected3

O+ MISCELLANEOUS C4$

>;. Are standoffs reuired2shown3

>=. Are safety straps shown3

>;. noc" outs wor" for customerPs press3

>=. noc" outs wor" for tryout press3

>@. est buttons designed to $tandard std3

>E. est button under return pins and sprue pins3

>. est buttons E-C apart on small molds and C-;> apart on large molds3

>C. Are e!ector screws reuired for pin plate3

>H. s .@> Y !ac" screw shown on or near +(3

;>. Are .@> Y dowels shown on +(3

;;. Are forward stops reuired3 f yes,

s there only 3

Are they near .1. and hydraulic e!ection cylinders3

;=. Are they support designed3

;


78/80

;. s the e!ector guide pin assembly to $tandards3

s the e!ector guide pin assembly design complete3

;@. Are handling holes shown X the same si%e if possible in all of the following

components3 a. Top of e!ector plate3

b. Top or retainer plate3

c. Top of clamp plate 4over E> also in ends53

d. )nds of rails3

;E. f uic" "ic"ers are reuired, are they designed3

;. s there clearance for lifter rod access3

;C. Are bolt holes reuired3 f so, is design complete3

;H. Does clamp plate reuire valve gate manifold accommodations3

a. #oc"ets for valve gate cylinders3

b. +hannels for valve gate plumbing3

c. s water reuired in clamp plate for valve gate cooling3

=>. s standard 8-/ut used for hydraulic e!ection3

=;. s all hydraulic plumbing shown3

a. Main ins and outs. 4Type3 (ocation35

b. Are flow dividers reuired3

==. s manifold electrical designed to customer specs3

=


79/80

e. Any special purpose plaues3

=. s stoc" list and purchase list complete3

=@. 8ave the final prints been sent to the customer3

=E. 8as the customer approved the designs3

Settin1 #n$ R!nnin1 ' #n In-e.ti'n M'*$

The ob!ective of this tas" is to provide an experience for a designer of an n!ection Mold,

to reali%e !ust what it ta"es to produce a part once the mold has been made. This is a special

opportunity to as" uestions of an expert in this area.

Be sure to as" uestions, be alert to all activities that ta"e place, and be sure to wor"L

R!*e%:


80/80

DO N't:

Touch or do anything, until you are told it is 1 by the instructor or Manager.

DO:

Ma"e an effort to ma"e the process as efficient as possible. Ma"e sure that you get a

part2runner.

N'te:

Bring $afety glasses, and, you may get a little grease on you clothes

so dress appropriately.

Position Main &ssistant

Manager

#hotographer'riter

#ower#oint

*runts

1nce, we are finished with the running of the mold, we will return to the classroom, and

create the ## presentation as a group. ## is due within Chrs.

The #ower#oint #resentation is simply a documentation of each and every step necessary

to create parts. $tarting with the Mold out of the press, and the plastic pellets in your handending up with the finished parts.

:ou should ma"e a copy of the ## for your records.

Documents

Mold Bases