Engineering Espresso Assignment

7/27/2019 Engineering Espresso Assignment

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There is no standardised process for making an espresso, every barista and every espresso machine will produce adifferent cup, that being said this definition of espresso courtesy of illy is great for the purpose of understanding : A jet ofhot water at 88-93 C passes under a pressure of nine or more atmospheres through a seven-gram cake-like layer ofground and tamped coffee. Done right, the result is a concentrate of not more than 30 ml of pure sensorial pleasure. Theinteresting thing about the espresso machine and any supposedly simple domestic item is the hours of engineering andtesting behind it. There are so many different parts and elements that must come together in harmony to produce theperfect cup of coffee. Its all about precision and consistency and finding the perfect balance between technology,tradition, convenience and flavour. Espresso arguably happens at the molecular level. This is why advancements inengineering and technology in general has had such a huge impact on the humble coffee.

During the 1800s, coffee was a gift to the European economy. The coffee industry was booming across all of Europe.Unfortunately for shop owners and baristas alike, achievingthe perfect brew was a tedious and painful process. It wasnot long before extravagant ideas were being realised andcrazy and wonderful inventions were being made. Sureenough the day came in 1884 when Angelo Moriondo filed apatent for what he called new steam machinery for theeconomic and instantaneous confection of coffee beverage.This early espresso machine was basically a gigantic boiler.Moriondos invention was indeed the first coffee machine touse both water and steam. Unfortunately it didnt go beyondthe patent itself, there hasnt been a single machine in hisname found nor photographic evidence. Moriondo was lostin history. He had the brains just not a business mind. Allthat remains of Moriondos concept is a patent with adream

Luigi Bezzerra and Desiderio Pavoni realised that dream.Bezzera made several improvements to Moriondosconcept, most importantly he introduced the portafilter aswell as multiple brewheads, and many other innovationsstill associated with espresso machines today. InBezzerasoriginal patent, a large boiler fitted with a built-in burnerchamber was heated until it pushed water and steam

through a tamped puck of ground coffee. The mechanismthrough which the heated water passed also happened tolower the temperature of the water from 120C in theboiler to the ideal brewing temperature of approximately90C. For the first time, a cup of coffee was ready to drinkin under a minute. The boiler however was heated over anopen flame, which made it nearly impossible to produce aconsistent coffee. Bezzera persisted and built a fewprototypes of his machine but his genious remained largelyunappreciated because he didnt have business knowhoweither. Thankfully he knew someone who did. DesiderioPavoni.
http://www.google.com/patents?id=xKpbAAAAEBAJ&pg=PA5&dq=luigi+bezzera&hl=en&sa=X&ei=DazgT9GdOsmf6AHXn9R_&ved=0CDYQ6wEwAA#v=onepage&q&f=falsehttp://www.google.com/patents?id=xKpbAAAAEBAJ&pg=PA5&dq=luigi+bezzera&hl=en&sa=X&ei=DazgT9GdOsmf6AHXn9R_&ved=0CDYQ6wEwAA#v=onepage&q&f=falsehttp://www.google.com/patents?id=xKpbAAAAEBAJ&pg=PA5&dq=luigi+bezzera&hl=en&sa=X&ei=DazgT9GdOsmf6AHXn9R_&ved=0CDYQ6wEwAA#v=onepage&q&f=falsehttp://www.google.com/patents?id=xKpbAAAAEBAJ&pg=PA5&dq=luigi+bezzera&hl=en&sa=X&ei=DazgT9GdOsmf6AHXn9R_&ved=0CDYQ6wEwAA#v=onepage&q&f=falsehttp://www.google.com/patents?id=xKpbAAAAEBAJ&pg=PA5&dq=luigi+bezzera&hl=en&sa=X&ei=DazgT9GdOsmf6AHXn9R_&ved=0CDYQ6wEwAA#v=onepage&q&f=false


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Pavoni bought Bezerras patents in 1903 and made a number ofimprovements. Pavoni invented the worlds first pressure releasevalve. For the first time hot coffee didnt splash from the release ofpressure. Previously scolding would often result. Pavoni alsocreated the steam wand allowing the steam that would inevitablybuild up to be reused. For a short time Bezzera and Pavoni workedtogether to perfect their machine, which Pavoni dubbed the Ideale.In 1906, at the Milan Fair, they introduced the world to what wenow call espresso. Bezzera sadly disappeared from the coffee scene,it is speculated he was bought out, but it is of no matter to us now,as Pavoni continued to introduce espresso to the world. Withcountless innovations, the Ideale marked the start of somethingvery special the birth of the modern espresso. After the Milan Fair,similar espresso machines began to popup throughout Italy.

Tothe

left is one of the surviving Pavoni espresso machines. Theseearly machines could produce in excess of 1000 coffees perhour, but relied exclusively on steam, which had theunfortunate side effect of a burnt or bitter taste in thecoffee. In addition it struggled to maintain even two bars ofatmospheric pressure, which interestingly by todaystandards is technically not even enough for the resultingconcoction to be considered espresso. As time inevitablypassed and electricity replaced gas and the chrome-and-brass aesthetic of the early 20th century passed, themachines did become smaller and more efficient, but theywere not able to achieve more than 2 bars ofpressure without burning the coffee.

Then along came Arduino, an inventor resolute on finding a method of brewing espresso thatdidnt depend on steam. Even though he thought of putting air pumps into the machines, he wasnever able to effectively incorporate his ideas. He did make an important contribution however,together with designer Leonetto Cappiello, creating the famous espresso poster that perfectlyencapsulated the nature of espresso. In the 1920s, Arduino was largely responsible for

exporting machines out of Milan and spreading the espresso across the rest of Europe.


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The man to finally surpass the two-bar brewingbarrier was Milanese caf connoisseur AchilleGaggia. Gaggia transformed the espresso machineinto a 50s chromed-out counter-top spunk withthe invention of the lever-driven machine. InGaggias machine pressure in the boiler forced thewater into a cylinder where it was furtherpressurised by a spring-piston lever operated bythe barista. It was very successful and drasticallyincreased the water pressure from 1.5-2 bars to 8-10 bars.

But that is not then end of the evolution. The next revolution in espresso machine was the Faema E61. Invented byErnesto Valente in 1961, the E61 introduced many more innovations and espresso firsts. Rather than relying on themanual force of the barista, it used a motorised pump to provide nine atmospheric bars of pressure. The pump also drewtap water directly from a plumbing line, through a spiral copper pipe inside a boiler before being shot through the groundcoffee, ensuring stable temperatures. With its technical innovations, smaller size, versatility and streamlined stainlesssteel design, the E61 was an immediate success.

There were other innovations throughout time, but these developments were the ones that changed espresso

forever. Over more than a century, the espresso machine has been reinvented and then reinvented again. The espressomachine advanced and so too did the technology behind it. But much like everything in this world, science andtechnology is not enough. There is an art to the espresso as well. The talent of the barista is as important as the quality ofthe beans and the efficiency of the machine.


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The simplest espresso machines use pressure from boiling water inside a sealedvessel. These types of machines can be bought for around $50, and there's even onethat is made especially to take on a camping trip. They all work on the sameprinciple, so by examining one we can understand in general how most simpleespresso machines function. In this type of machine, shown to the left, the coffee ispacked into a funnel-shaped piece of metal that has a tube extending to the bottomof the reservoir. About 50mL of water is put into the reservoir and the top isscrewed on.When the water is heated over the stove, pressure builds inside the vessel, and theonly way for it to escape is up the tube, through the coffee and out of the tube in the

top. Since the end of the tube is under water, the pressure forces the hot water up through the tube. There are somedisadvantages to a machine like this. The pressure in the system depends on the temperature of the water. Thetemperature required to build up enough pressure to force the water through the coffee might exceed the ideal brewingtemperature. This is why higher quality domestic and commercial machines utilize a pump.

Pump-style Espresso MachinesThis type of machine is a little fancier, but is still fairly simple to operate.Let's start by seeing how the machine is put together. The reservoir holds the coldwater used in the espresso machine. It is not pressure-tight or heated, and it isremovable.

The pump draws water out of the reservoir and pumps it into the heating chamber at high pressure.

Heating ChamberThe heating chamber is made of stainless steel with a resistive heating element built into agroove in the bottom. The resistive heating element is like the filament of a light bulb whencurrent passes through the element due to its high resistance, heat is created. In the heatingchamber the resistive element is placed in plaster to make it more durable. There is also a one-way valve that ensures water is let into the chamber from the pump, but not back the other way

The porta-filter is the detachable part that holds the ground coffee.Inside the metal basket is a small screen into which the ground coffee istamped. On the bottom of the porta-filter there are two spouts whichallow the coffee to drip out.

The steam wand allows built up steam to be used to heat and froth milk for use in various espresso drinks.This wand is connected to the heating chamber. Usually there will be a switch to allow steam from theheating vessel to be released out of the wand and into the milk instead of the porta-filter.

Control PanelThe control panel usually contains the on/off switch, two indicator lights and a control valve, but ofcourse different models would contain different features and thus different buttons. One of the lights generally indicatethe power state while the other would indicate when the optimum temperature has been reached.
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Boiler: Espresso machine boilers can range in size from 120mL in domestic machines to12000mL and over in commercial machines. They are made of a brass alloy, stainless steel oraluminium.

Burrs: Burrs used in espresso grinders are flat in lower end models and conical in premiumvariations. They must be sharp and tight fitting in order to provide the precision necessary

for optimum grinding. Burrs are almost always made of steel.

E-61 Group. Originally created by Faema, this group is made of 4kg quality chrome platedbrass, designed to act as a temperature stabiliser. It brought unparalleled temperaturecontrol to the espresso machine. Its success has seen it starting to appear on domesticmachines as well.

Grinder: Commercial espresso grinders use conical burrs and almost always come with adoser attached. Domestic grinders can also have dosers, or be doserless. All espressogrinders come with rests for the portafilter.

Filter baskets: Stainless steel baskets of various size, shape and depth with holes in the base.Ground coffee is tamped into the basket and the assembly is then locked into the groupbefore brewing commences.

Group: Sometimes called the brew-head, is where the portafilter locks into, and wherepressurised hot water is forced through the coffee in the filter basket. It consists of a metalcylinder with passages in it for water, and sometimes has various valves built in.

Group Gasket: The rubber ring is inserted in the group to ensure that the portafilter andfilter basket combination seal tightly, stopping leaks. The rubbers used in group gasketstend to harden with age and should be replaced when they no longer seal properly.

Portafilter: The portafilter holds the filter basket, and locks into the group to provide awatertight seal for the pressurised water to infuse the coffee. The espresso then exits theportafilter via the spouts. Portafilters normally have double spouts, but triple spoutvariations are available to purchase. Domestic portafilters always have 2 spouts.

Rotary Pump: Most commercial espresso machines use rotary pumps connected to anelectric motor. The pumps is actually fairly small, it is the electric motor that takes much ofthe space.


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Showerscreen: a small perforated stainless steel disk which showers water from the grouponto the coffee in the filter basket. In high end and commercial machines the disk consists oftwo parts; a solid stainless steel disc back with relatively large holes and a fine stainless steelmesh front, which provides light and even showering.

Solenoid 3 - way Valves: These valves serve to relieve the built up pressure in the group andportafilter assembly immediately after brewing. They are usually electronic but mechanicalversions of this valve also exist. They are readily found in high end domestic machines and

all commercial machines.

Tamper: The Tamper is really a presser that ensures there are no gaps in the coffee wherepressurised water could pass.

Thermoblock: A metal block with a large number of narrow channels inside, heated by anexternal element. They are generally used in cheaper, lower quality espresso machine.

Vibration Pump: Pump domestic espresso machines and some of the lower end smallcommercial machines use vibration pumps. They provide pressure.

Boilers are usually made of aluminium, stainless steel of brass. Aluminium Boilers are usually less expensive andnormally have average corrosion resistance. Stainless Steel Boilers have good heat retention properties and arevery resistant to corrosion. Copper / Brass boilers, are the best of all at resisting corrosion. Their heat retentionproperties are also extremely good.

Burr grinders are made of a variety of steels allowing them to grind effectively while rotating relatively slowly,usually below 500 rpm, reducing frictional heating of the ground coffee. The higher end models use a caststainless steel lower end models generally use a sintered alloy of steel and zinc.

Chrome plated brass is used to manufacture the E61 group, it provides high thermal inertia, that is, It takes along time to heat up and cool down. This is the primary reason behind its popularity and its continued use today,it was one of the first designs to provide actual temperature stability. The main internal chamber of the E61group is connected to the boiler by two copper pipes. The copper has good heat retention properties.

Grinder casing generally use a BPA free composite. The plastics are favourable because they are cheap and easyto shape as well as being transparent and offering low thermal conductivity.

Filter baskets are made using a stainless steel. As they are often in contact with wet coffee and washedfrequently, stainless steel is the alloy of choice due to its brilliant lustre, corrosion resistance, and mostimportantly dishwasher safe.

The Group is also made of a stainless steel. Higher end variants employ a steel tungsten alloy to minimiseexpansion at high pressure and extreme heating.

Group gaskets are generally made of BPA free rubber. The rubber offers a tight waterproof seal and can beeasily replaced by the home user. The rubber maintains the seal at high temperatures unlike most metals.

Portafilters are usually made of chrome-plated brass, which is used for its heat stability properties, durability andbrilliant lustre. Cheaper variants are made of aluminium with plastic handles, which are not as good atmaintaining heat stability and not as durable. Aluminium is also duller than chromium and thus used in cheapermodels.


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The rotary pumps are made of brass, for its durability, heat retention, corrosion resistance and general

toughness.

The showerscreen is made of stainless steel. Higher quality variants also employ a stainless steel mesh that actsas a sieve for better water spread.

The solenoid head much like the rotary pump is made of brass. Brass is the metal of choice for the same reasons,durability, heat retention, corrosion resistance and general toughness. The casing is made of plastic because ofits low thermal conductivity.

The tamper is made of plastic or stainless steel, plastic or wood. Higher end models obviously use stainless steelfor its lustre and durability. The tamper is often visible outside the espresso machine as a showpiece of sortsthus, the plastic tampers are found in cheaper domestic variants.

The thermoblocks are made of aluminium. Aluminium has average thermal retention properties but the mainreason it is chosen is oddly because of its low density and malleability not its thermal properties. Because thethermoblocks are made of intricate channels aluminium is the cheap metal of choice, other metals are difficult toform intricate channels with.

The vibration pump is made of brass with casing made of plastic much like the solenoid. The brass is used for thesame reason however plastic is used because it is also easy to manufacture into the intricate shapes that arerequired small spaces can cause great damage because of the vibrations and thus a snug casing is of absolute

importance.

The pros and cons of different materials:

Aluminium is an extremely light pure element and has about one third the density of steel. Aluminium is resistant tocorrosion in most environments. Aluminium is also very good at conducting heat. In addition Aluminium is readilyavailable because it is relatively abundant. As a result of aluminium it is extremely malleable. Unfortunately aluminium isnot very strong, the strongest varieties have 75,000 psi tensile strength compared to 240,000 psi tensile strength for thestrongest varieties of steel. Aluminium is not very hard and as a result is easy to scratch. Aluminium is also moreexpensive than steel of the same strength.

Stainless steel is a tough alloy consisting of steel(iron, carbon) as well as manganese, tungsten and chromium. A well-maintained stainless steel appliance can last for several decades before requiring servicing or needing to be replaced.

Stainless steel appliances are quite resistant to rust as well as germ and bacteria growth. Stainless steel appliances arerelatively easy to clean since they do not stain easily. Special stainless steel cleaning materials can be purchased at mosthome improvement stores. Stainless steel is relatively hard and extremely durable. One of the biggest disadvantageslinked with stainless steel appliances is their initial purchase cost. Stainless steel also tends to scratch and dent. Food,grease and fingerprints show very clearly on stainless steel, making frequent wiping and cleaning a necessity. Stainlesssteel is also difficult to shape as it is not as malleable as other metals and is costly to re-work after damage. Stainless steelis also tough to weld and polish.

Brass is an alloy of copper and zinc. The advantages of brass include its excellent corrosive resistance and its joining,plating, polishing and finishing characteristics. Brass is easily machined and is extremely durable. In addition it hasextremely good thermal retention. Unfortunately brass requires a good deal of maintenance since it is prone to a blackishtarnish thus it is usually plated in chromium or kept hidden inside the espresso machine and is rarely exposed. Thebiggest challenge to maintain most metals, including brass, is the removal and inhibition of tarnish.

Plastic is a durable polymer, it is designed to withstand small disturbances. The thicker the plastic the more durable it ismuch like glass. However, plastic is cheaper than other common materials, such as glass, metal and wood. It ismanufactured in great quantities, which means the overall cost is low. Plastic is used in food storage because containersare often damaged in everyday use and misplaced over time. There is a low cost associated with replacing thesecontainers. Plastic does degrades over time but it does not decompose. The material is affected by excessive light,scratching, denting and cracking. If you leave plastic containers stacked with heavy items in them for a long period oftime, the plastic will buckle and crack. For example, a glass container for food storage has a longer life than a plastic one,as long as the glass does not break.

Unfortunately plastic, absorbs the smells and tastes of items stored in them. This is why plastic is only used in thecasings of espresso machine if it were used in the reservoir; showerscreen or filter basket the smell would linger forever.Materials, such as glass and metal, do not absorb flavours and are better to use in these areas.

Rubber is also a polymer. On one hand, rubber has the particular advantage of high elasticity and resistance. What'smore, rubber does not break easily compared with gaskets made of other materials. Rubber also has the superiorcapability of moldability. Thus, it is widely applied in many fields. On the other hand, rubber has the disadvantage ofbecoming sticky under high temperature. Rubbers are also relatively soft and unfortunately harden over time whichmeans they essentially lose all the properties they are favoured for and must be replaced.


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Blind Rivets, Screws, Nuts and Bolts.

Rivets are very useful. They are easy to fasten. They can be put in when you can only access one side of the job and theycan even be taken out. They are usually used to secure sheet metal. Appliances with rivets cannot have the rivets undonethen put back together, so therefore they are not as common in household appliances. So places you will find rivets in thehome include knives, and other cutlery.

Blind rivets (also known as pop rivets, because of the sound they make) are joining device which include a rivet heat and amandrel through the center. The rivet is pushed through a predrilled hole though the parts desired to be joined and arivet gun is used to draw the mandrel into the rivet. The result is expansion of the blind end of the rivet. These types ofblind rivets have non-locking mandrels which means at any point in time the mandrel could fall out and leave a hollowrivet which would have a much lower load carrying strength. Furthermore, because of the mandrel they often fail due tocorrosion and vibration. So why are they used at all. Well, mainly for convenience, blind rivets can be fully installed in a

joint from only one side of the job, essentially "blind" to the other side.

Due to this feature, blind rivets are primarily used when the other side of a joint cannot be accessed. The rivet is placed ina drilled hole and is set by pulling the mandrel head into the rivet body, expanding the rivet body and causing it to pushagainst the reverse side. As the head of the mandrel pushes closer to the blind side, resistance inevitably increases, and ata predetermined break point, the mandrel snaps, when the pulling force exceeds the strength of the break point. A tight

joint is all that remains, the head of the mandrel usually can be found inside the rivet body. Blind rivets are available inmany variations, flat head, countersunk head, and modified flush head with diameters of 1/8, 5/32 and 3/16 inch. Blindrivets are usually made from soft aluminum alloy but also sometimes in steel (including stainless steel) and copper.

Screws are really simple, they are either machine or hand screwed into the work. Sometimes a skinny hole is cut into thejob, sometimes the screw will cut its own way in. Screws are probably the most common type of joining method used inhousehold appliances. They can also be taken out and be put back in easily by even a domestic user. You would findscrews in all kinds of appliances ranging from toasters to vacuum cleaners to electrical appliances such as radios TVs andtorches.

A screw is a cylindrical fastening device with a ridge, commonly referred to as the thread. Some screw threads aredesigned to screw into a complementary thread often called the internal thread. Other screw threads are designed to cuta helical groove in a softer material (such as wood) as the screw is inserted. The most common uses of screws are to holdobjects together and to position objects.

A screw will always have a head, this is the top end of the screw that allows it to be driven. The most frequently used tool

to drive screws is appropriately named the screwdriver other tools can also be used like wrenches, drills etc . The head isalmost always larger in diameter than the body or cylindrical part of the screw, this ensure the screw does not penetratebeyond the length of itself whilst also providing a bearing surface. The cylindrical portion of the screw from theunderside of the head to the tip is known as the shank; it is usually completely threaded but sometimes they are partiallythreaded. The distance between each ridge or thread is known as the "pitch".

The majority of screws are tightened by clockwise rotation, this gave rise to the now well known mnemonic "righty-tighty, lefty-loosey." However, there are some screws tightened by counterclockwise rotation. For example, when thescrew is prone to counterclockwise torque, a counter clockwise screw would be an appropriate choice, as a standard screwwould loosen itself. This is why the left side pedal of a bicycle has a counterclockwise thread and must be tightened in theopposite direction to the right side pedal.

Screws and are usually made of steel. Where great resistance to weather or corrosion is required, like in very smallscrews or medical implants, materials such as stainless steel, brass, titanium, bronze, silicon bronze or monel may be used.

Nuts and Bolts are used to fasten objects together. They can fasten all sorts of materials ranging from metals to timbersto plastics. Firstly a hole is cut through the work, next the bolt is placed through with a washer on the bottom end. Thena nut is screwed on to the end of the bolt, and then fastened with a spanner. Nuts and bolts are usually made from steel.Nuts and bolts are used to fasten things that need to be able to be undone and put pack together, they are used in placeswhere screws are just too weak.

Bolts are very similar to screws in design and function but they are generally larger and do not taper towards the tip likemany screws as they are not required to cut materials. Bolts have a thread much like screws but they do not cut into thematerial to create a join rather they simply are placed through a hole and a complementary nut used to fasten them.

A nut is a type of fastener with a threaded hole. When vibration or rotation may cause a nut loose, Self locking nuts canbe used with: Adhesives, safety pins or lockwire, nylon inserts, or slightly oval-shaped threads. Nuts are usually

hexagonal, for similar reasons as the bolt head - 6 sides provide the best angles for a tool to approach from tight spots,any more corners would be vulnerable to being wear and rounding. Of course there are exceptions and other specialisedshapes do exist for certain needs, such as wing nuts for finger adjustment and captive nuts for inaccessible areas.

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Engineering Espresso Assignment