Hard Chrome Plating Training Course

Contributing Authors
Larry Zitko, ChromeTech
George Cushnie, NMFRC
Paul Chalmer
Randy Taylor, Advanced Tooling Corp.

Table of Contents

Section 1: Course Overview

Section 2: Introduction To Hard Chrome Plating

  • What is Hard Chrome Plating?
  • Hard Chrome vs. Decorative Chrome
  • Why We Use Hard Chrome
  • Hardness
  • Abrasion Resistance
  • Low Coefficient of Friction
  • Good Adhesion
  • High Oil Retention
  • High Melting Point
  • Thermal Conductivity
  • Lubricity
  • Corrosion Resistance

Section 3: Process Chemistry And Equipment

  • Chromium—Chemical Terminology
  • Types of Plating Baths in Common Use
  • Conventional, Single-Catalyst Bath
  • Fluoride, Mixed-Catalyst Bath
  • High-speedn Non-etch, Proprietary Bath
  • Electricity and Hard Chrome Plating
  • Power Supplies Used for Hard Chrome Plating Systems
  • Factors in Choosing a Power Supply for Hard Chrome Plating 9
  • Air Cooling vs. Wate Cooling for Power Supplies
  • Rectifier Bussing and Tank Bus Bars
  • 3 Bus Bar Design
  • 2 Bus Bar Design
  • Tanks
  • Chrome Plating Tanks
  • Environmental Releases of Chromium from Plating Tanks
  • Alkaline Electrostrip Tanks
  • Scrub/Clean/Electroclean Tanks
  • Rinse Tanks
  • Anodes
  • Solution Heating
  • Solution Cooling
  • Solution Agitation
  • Exhaust Ventilation and Air Pollution Control
  • Encapsulating Hood
  • Exhaust Fans
  • Environmental Releases of Chromium to Air
  • Air Pollution Control

Section 4: Plating Procedures

  • Preplate Analysis
  • Stress Relief Bake
  • Shot Peen
  • Pre-cleaning
  • Masking
  • Racking/Fixturing
  • Cleaning
  • Water Break Test
  • Activation/Etch
  • Chrome Plating
  • Amps vs.Volts
  • Rinsing
  • Hydrogen Embrittlement Relief
  • Chromium Stripping
  • Plating on Special Base Metal

Section 5: Troubleshooting

  • Poor Chrome Appearance
  • Poor or Partial Coverage
  • Anode Placement and Size
  • Poor Throwing Power
  • Trees
  • Poor Adhesion
  • Roughness
  • Pitting
  • Arcing
  • Poor Corrosion Resistance
  • Micro-Cracking
  • Macro (Mud) Cracking
  • Slow Plating Rates
  • Uneven Chromium Deposition
  • Wild Chrome

Section 6: Plating Bath Impurities And Treatment Technologies

  • Analytical Data
  • Preventing Contamination and Removing Contaminants
  • Trivalent Chromium (Cr+3)
  • Metallic Impurities - Tramp Metals
  • Metallic Impurity Limits
  • Dummy Plating
  • Ion Transfer - Porous Pot
  • Ion Transfer - Membrane Type
  • Advanced Membrane Technologies
  • Ion Exchange
  • Chloride
  • Suspended Solids
  • Oil and Grease

Section 7: Health And Safety

  • Health Risks Associated with Exposure to Hexavalent Chromium
  • Skin Contact
  • Ingestion
  • Breathing
  • Additional Safety Measures
  • Protect Yourself in Case of an Accident

Section 8: Pollution Prevention

  • What is Pollution Prevention (P2)?
  • Benefits of P2
  • P2 in Action
  • Rinse Water P2 Techniques
  • Rinsing
  • What is Hazardous Waste?
  • Prevent Bath Contamination
  • Air Emissions
  • P2 Implementation
  • P2 Summary

Appendix 1: Answers to Quizzes
Appendix 2: Acronyms and Abbreviations
Appendix 3: Reverse Etch Times
Appendix 4: Calculation of Surface Area
Appendix 5: Plating Parts Using a Plating Log
Appendix 6: Amps vs.Volts
Appendix 7: Troubleshooting Summary
Appendix 8: Conversion of Degrees Baumé to Concentrate for Chromic Acid
Appendix 9: Tracking Down Voltage Drops
Appendix 10: Conversion of Units
Appendix 11: Glossary




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