Making Hard Chrome Plating Greener - CASF€¦ · High efficiency system for ‘greener’ plating of shock rods System design optimized for shock absorber rods High efficiency, high

General Metal Finishing

Making Hard Chrome Plating Greener

Neil Patton, CASF Conference, Ontario, 13.11.2013

2 General Metal Finishing

Hard Chrome Plating Benefits

3

Benefits of Hard Chrome Hard Chrome Deposit Characteristics


Greater hardness

Lower coefficient of friction

Improved wear resistance

Higher galling resistance

Chemical inertness

Superior corrosion resistance

Low linear expansion

4

Benefits of Hard Chrome Benefits of Hard Chrome Plated Parts


Hard Chrome Plated Parts Are very hard

‒Less wear ‒Longer part lifetime

Have superior tribological properties ‒Less friction ‒Less wear ‒Less heat generation ‒Less energy wastage

Corrode less ‒Longer part lifetime

Are easily repaired ‒Longer operational lifetime


The Green Issues with Hard Chrome Plating

6

Green Issues with Hard Chrome Plating Legislation e.g. REACH for Chromium Salts


Cr6+ Compounds require authorization

Cr6+ compounds have been added to Annex XIV

A consortium is preparing the authorization for Chromium Trioxide and its acids >150 participants

Name CAS Number Chromium trioxide 1333-82-0

Chromic acid 7738-94-5

Dichromic acid 13530-68-2

Sodium chromate 7775-11-3

Sodium dichromate 10588-01-9

Sodium dichromate dihydrate 7798-12-0

Potassium chromate 7789-00-6

Potassium dichromate 7778-50-9

Ammonium dichromate 7789-09-5

April 17 2013

Inclusion in Annex XIV

March 21 2016

Latest Application Date

September 21 2017

Sunset Date

7

Green Issues with Hard Chrome Plating Use and Generation of Hazardous Substances


Hard Chrome plating involves several highly hazardous substances

Pb

Pb Oxide

Pb Chromate

Chromium Trioxide

Sulfuric Acid

Also Possibly

Fluoride Catalyst

PFOS

Barium Carbonate

8

Green Issues with Hard Chrome Plating Exposure to Hazardous Substances


There can be a lot of hazardous substance handling and exposure

Adding: Chromic Acid Sulfuric Acid Barium Carbonate

Sample Taking

Spills / Leaks

Anode Maintenance Chromic Acid Mist

9

Green Issues with Hard Chrome Plating Emissions of Hazardous Substances


Hard Chrome plating emissions can be solid, liquid or airborne

Spills / Leaks

Anode Maintenance Chromic Acid Mist

Dosing Containers

Drag-out into Rinses

Scrapping Anodes

Sludge Removal

Liner Replacement

Line Cleaning

Line Maintenance

10

Green Issues with Hard Chrome Plating Resource Wastage


Hard Chrome plating processes can waste a lot of resources

Low Cathodic Efficiency

G

Dissolution of Anodes

Excessive Localized Plating (Dog boning)

Bath Drag-out

Excessive Contamination (Increasing Dog boning and plating problems)

Chromic Acid Mist


Replacing Hazardous Substances

12

Replacing Hazardous Substances Cr6+ Replacement


So far Cr3+ based processes are only available for decorative applications

Alternative Technologies for a 1:1 replacement of Hard Chrome are

not yet available

Alternatives for specialist applications ‒ HVOF – High velocity oxygen fuel thermal

spray process (printing rolls, etc…) ‒ Electroless Nickel coatings tempered for

complex shaped parts

Functional Trichrome processes are being developed

So far there is no commercial Cr3+ Hard Chrome process available

13

Replacing Hazardous Substances Pb Replacement


Pt/Ti anodes can be used to eliminate Pb from Hard Chrome plating

Pb/Sn anodes are in common use for Hard Chrome ‒ Cheap ‒ Easily formed

Platinized Titanium (Pt/Ti) anodes are a suitable alternative

Pt/Ti anodes have a higher initial investment cost but ‒ Generally last years significantly longer lifetime than Pb/Sn ‒ Require less maintenance reducing downtime ‒ Don’t generate Pb-Chromate sludge can easily agitate bath ‒ Don’t need to be dummied in immediate start-up ‒ Can reduce plating voltage reduced electrical costs ‒ Keep form stable don’t change shape keeping plating constant ‒ Easily formed in desired shapes enabling better plating distribution ‒ Weigh significantly less than Pb/Sn easier to work with and change

Courtesy of Umicore

14

Replacing Hazardous Substances Fluoride Catalyst Replacement


Better efficiency with less base material and equipment attack

Use an organic based secondary catalyst process which gives:

Higher plating efficiency ‒ Less energy wasted ‒ Higher plant utilization

Lower etching of parts, anodes and equipment ‒ Less maintenance required ‒ Less metallic contamination longer bath lifetime

Better deposit quality ‒ Lower friction ‒ Harder surface ‒ Higher wear resistance longer part lifetime ‒ Higher corrosion resistance longer part lifetime

Taber Wear Test

Less wear

15

Replacing Hazardous Substances PFOS Replacement


PFOS can be eliminated by using non-PFOS mist suppressants

PFOS is banned in several countries with limited exemptions

Hard chrome plating currently has an exemption for the use of PFOS ‒ In Canada the exemption ended on May 20, 2013 ‒ In the USA the exemption ends on September 21, 2015

There are now viable alternatives that meet EU Directive 75/769/EEC and US EPA SNUR 40 CFR 721.9852…

There are several non-PFOS and even non-PFC mist suppressants available

They are industry proven


Greener Equipment Developments

17

Greener Equipment Developments Pt/Ti Anodes


Pt/Ti anodes can give technical as well as HES advantages

Pt/Ti anodes are more form stable than Pb/Sn ‒ No bending over time ‒ Less maintenance required

Pt/Ti anodes last longer ‒ Less maintenance downtime ‒ Reduced long term costs ‒ Less waste

Pt/Ti anodes can be easily formed to improve plating distribution ‒ Less over plating ‒ Less waste

18

Greener Equipment Developments Conformal Pt/Ti Anodes


Conformal anodes can significantly reduce overplate

Parts

Typical Arrangement of Pb/Sn Anodes angled view

Resulting Plating Distribution Typical Conformal Anodes Arrangement

19

Greener Equipment Developments Water Recycling Concepts


Reduced water usage and wastewater emissions

Water recycling concepts can reduce water consumption considerably ‒ Reduced DI water demand ‒ Reduced rinse water demand ‒ Reduced wastewater amount ‒ Combined with ion exchange can reduce contamination and improve the part lifetime

20

Greener Equipment Developments Plating Line Housing


Staff and local area protection

Utilization of housing to reduce Cr6+ exposure of staff ‒ Also helps to reduce emission of Cr6+ into the local surroundings

21

Greener Equipment Developments Liquid Additives and Pumped Dosing


Simpler and more controlled dosing with less dust

Liquid products for the Cr6+ additives can prevent excessive dust being emitted into the surrounding areas during dosing

The use of a pumping station for liquid additives reduces staff exposure to Cr6+during dosing operations

22

Greener Equipment Developments Pumped Sample Taking Systems


Reduced exposure of staff to Cr6+ and less Cr6+ line contamination

By incorporating a pumping system and pipework for taking samples from etch and Chrome tanks exposure of staff to Cr(VI) can be reduced ‒ Staff don’t need to enter the line so reducing exposure and risk

23

Greener Equipment Developments Improved Ion Exchange


Improved ion exchange system reducing waste by >50%

Ion Exchange Benefits ‒ Newly developed IX-system with significant wastewater savings

Significant advantages over currently used IX systems ‒ 50 % savings in wastewater ‒ Higher level of safety ‒ Lower energy consumption

24

Greener Equipment Developments Specialist Equipment for Shock Absorber Rods


High efficiency system for ‘greener’ plating of shock rods

System design optimized for shock absorber rods

High efficiency, high productivity equipment and chemistry

Reduces excessive local plating

Conventional manufacturing process

Raw

MaterialHardening Grinding Cleaning Chrome

Plating

OptionalHydrogen

Deembrittle-ment

Super-finishingand / or

Polishing

Raw

MaterialHardening Grinding Cleaning

ChromePlating

OptionalHydrogen

Deembrittle-ment

Grinding

Super-finishingand / or

Polishing

DYNACHROME –Integrated Manufacturing Process

25

Greener Equipment Developments Specialist Equipment for Shock Absorber Rods


Removal of Pb, no excessive plating and reduced waste emissions

Use of conformal Pt/Ti anodes removes the need for Pb/Sn anodes

Special wastewater concept reduces emissions and water usage

New chemistry reduces build-up of key contaminants

50% less chemistry 50% less electricity

No grinding

26

Greener Equipment Developments Continuous Platers for Hydraulic Rods


Severely reduced bath volume and enclosed plating

Current density 65 - 120 A/dm² ‒ High productivity

Separate Etching and Plating ‒ Better solution management ‒ Less waste

Lower total bath volume

Enclosed modules ‒ Reduced exposure ‒ Better emissions control

Uniform plating distribution ‒ Less post-grinding ‒ Reduced chemistry consumption


Greener Process Developments

28

Greener Process Developments Trivalent Chromium Control (TCC) for Pt/Ti Anodes


Significant improvement in conductivity with lower Cr3+

TCC technology improves the Cr3+ Cr6+ re-oxidation for Pt/Ti anodes

Lowers and controls Cr3+ contamination for Pt/Ti anode systems

Less metallic contamination higher bath purity

Higher quality Chrome deposit

Longer potential bath life

Reduced ion exchange usage or dummy plating

Lower chemical consumption

Lower wastewater discharge and energy consumption

Improved conductivity through Cr3+ control

29

Greener Process Developments TCC Example for Rotogravure


Stable and Pb-free process delivering high quality rolls

Effective Cr3+ to Cr6+ re-oxidation under normal plating conditions

Less down time for dummy plating etc…

Completely Pb-free and no need for auxiliary Pb anodes

Helps keep consistent plating quality Cr(III) Development

0

2

4

6

8

10

12

14

0 5 10 15 20 25 30 35 40 45 50kAh

[Cr(

III)]

(g/l)

30

Greener Process Developments Non-PFOS Mist Suppressants


Non-PFOS and Non-PFC mist suppressants are available

There are several non-PFOS mist suppressants on the market ‒ Foaming ‒ Low-foaming

There is now the 2nd generation of low-foaming mist suppressants ‒ Some are even non-PFC (PerFluorinated Compound)

Foaming Type Low-foaming Type Low-foaming Type

31

Greener Process Developments Non-PFOS Mist Suppressants – Surface Tension Measurement


Surface tension analysis of Non-PFOS mist suppressants is different to PFOS based mist suppressants – TAKE CARE!

Surface tension measuring of Non-PFOS mist suppressants respond slightly differently to PFOS based mist suppressants ‒ Especially by stalagmometer

Stalagmometer to Tensiometer difference generally ≈10 mN/m

Stalagmometer to Tensiometer difference 8-25 mN/m

32

Greener Process Developments Mist Suppressants – Surface Tension Correction Factor


Ensure to use relevant correction factors, if necessary

Commonly du Noüy rings tensiometers are used to measure surface tension of hard chrome baths utilizing mist suppressants ‒ This requires a correction factor ‒ Correction is needed due to the weight of the liquid pulled up with the ring during measurement

The factor for a du Noüy ring method can be calculated dependent on the

‒ Radius of the ring ‒ Radius of the wire used for the ring ‒ Density of the solution being measured

A factor can change a reading by up to 4-5 mN/m ‒ 33 mN/m measured 29.2 mN/m corrected

Having the wrong reading can lead to excessive foaming and mist suppressant usage

33

Greener Process Developments Sulfuric Based, Non-electrolytic, Cr Stripper


Sometimes Cr plated parts need to be stripped

Common technologies employed are ‒ Electrolytic systems Alkaline or Acidic

‒ Immersion systems Typically Hydrochloric Acid based

To reduce the need for rectifiers and cathodes immersion stripping is typically chosen over electrolytic

But HCl can fume making it unfriendly for operators

There are now Sulfuric based immersion strippers on the market ‒ No HCl fuming ‒ Faster than HCl alone ‒ Less base material attack


Summary

35

Greener Process Developments Summary


Hard Chrome plating still has a place in today’s society and greener technologies can be made more HES friendly

The hard chrome coating of parts brings valuable benefits ‒ also HES benefits

Basically, all but the Chromic Acid and Sulfuric Acid hazardous substances can be replaced today in the Hard Chrome plating bath

There are suitable technologies available to reduce exposure to operators

There are suitable technologies available to reduce emissions

There are suitable technologies available to reduce the waste of resources

Some of these technologies can also improve quality and productivity making them also cost effective


Thank you for your attention!

Documents

Making Hard Chrome Plating Greener - CASF€¦ · High efficiency system for ‘greener’ plating of shock rods System design optimized for shock absorber rods High efficiency, high