Chrome Auto Plating Gains Despite Challenges

A dozen European companies are eyeing increased opportunity to plate injection molded plastic parts as car makers, particularly in Europe and Asia, are stepping up efforts to reduce weight with plastic-for-metal substitutions.

More than 26 interior and exterior parts are plated, particularly in high-end cars even though chromium is a known carcinogen and is listed as a hazardous air pollutant. It provides a mirror-like surface finish, good corrosion resistance and strong aesthetic appeal and substitutes are said to be inferior. Strict environmental rules are in place at plating operations.

The chrome plating process is highly complex and can consist of as many as 30 steps.

Plastic plating (sometimes called galvanizing) is also tricky because any type of surface blemish is magnified. Another challenge is OEM interest in using materials beyond standard ABS, which has been plated for more than 50 years. The butadiene helps in the plating process.

One increasingly used plastic is ABS/polycarbonate T65, which has high PC and low ABS content. Other examples of materials hard to galvanize are 30 percent glass-reinforced polyamide 6 and 50 percent glass-ball reinforced PA6. Sometimes two (2K)- and three (3K)-component moldings are selectively plated. Polyamide blended with 40 percent mineral filler has high tensile strength and is used for special applications such as interior door handles

Use of chromium as a plating agent is said to provide:

  • Excellent corrosion and chemical resistance;
  • Wear and abrasion resistance;
  • Very good adhesion;
  • A high-class surface with mirror-like reflection or aluminum-like matte surfaces; and
  • Hardness, scratch resistance.

Excellent interaction between the injection molding and galvanization processes is required for successful application of the surface finish to materials.

The process starts with etching with a chromic solution to remove the butadiene from the top of the substrate. That creates pits that act as anchor points for the subsequent nickel and other layers. During the electroplating process, chromium  is reduced to metallic chrome.

The European players are Gerhardi Kunststofftechnik GmbH, C. Hübner GmbH, BIA Kunststoff- und Galvanotechnik GmbH & Co KG, Heinze Gruppe GmbH, Bolta Werke GmbH, Boryszew Oberflächentechnik Deutschland GmbH, WAFA Germany GmbH, Aludec Galvanic s.a., C+C Krug GmbH, Fischer GmbH & Co. surface technologies KG, SAXONIA Galvanik GmbH, Karl Simon GmbH & Co. KG. They operate 22 sites in Germany, Spain, Slovakia,  and the Czech Republic.

At least one of the players integrates the process from design and toolmaking through injection molding and electroplating.

Boryszew Oberflächentechnik Deuschland of Prenzlau, Germany currently employs 348 workers and is planning to reach $38 million in sales in 2017. The company’s main market is Germany, but also exports to America and Asia. Boryszew Prenzlau realizes 90 percent of its sales with automotive parts for both interiors and exteriors of vehicles, such as decorative strips or door handles. Its main customer is the VW/Audi group.

Boryszew Oberflächentechnik Deutschland operates 25 injection molding machines with clamping forces ranging from 88 to 785 tons, 13 of which have come from Wittmann Battenfeld. The company also uses the Airmould internal gas pressure technology from Wittmann Battenfeld, since the weight of automotive components plays an important role. Variothermic technology from Wittmann Battenfeld is used for sensitive surfaces.

Injection molded, chrome-plated door handles embedded in a complex assembly. (Wittmann Battenfeld)

About Doug Smock

Former Chief Editor at Plastics World and Senior Technical Editor Design News
ABS, Automotive, Europe, Foam molding, Injection Molding, Molds & Moldmaking, Polyamides, Polycarbonate ,

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