making hard chrome plating greener - casf€¦ · high efficiency system for ‘greener’ plating...
TRANSCRIPT
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
5 General Metal Finishing
The Green Issues with Hard Chrome Plating
6
Green Issues with Hard Chrome Plating Legislation e.g. REACH for Chromium Salts
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
11 General Metal Finishing
Replacing Hazardous Substances
12
Replacing Hazardous Substances Cr6+ Replacement
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
16 General Metal Finishing
Greener Equipment Developments
17
Greener Equipment Developments Pt/Ti Anodes
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
27 General Metal Finishing
Greener Process Developments
28
Greener Process Developments Trivalent Chromium Control (TCC) for Pt/Ti Anodes
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
34 General Metal Finishing
Summary
35
Greener Process Developments Summary
Neil Patton, CASF Conference, Ontario, 13.11.2013
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
36 General Metal Finishing
Thank you for your attention!