Carmakers today are facing a multitude of challenges, ranging everywhere from strict emission targets to falling sales levels. In this industry, cutting costs has become a major priority. That means that now may be the right time to take another look at moulded-in-colour parts: using masterbatch instead of paint for metallic-effect parts.
Transitioning from paint to masterbatch for metallic-effect parts, obviously, is not new. And while paint adds a great surface finish to automobile parts, painting always adds cost, time, and additional logistics requirements, said masterbatch producer PolyOne, who recently collaborated with a leading global automotive OEM and its injection moulder to eliminate paint from a new vehicle’s interior.
Using PolyOne’s Smartbatch FX metallic masterbatches, the moulder was able to produce parts - two PC/ABS side panels on the centre console of a compact SUV now entering commercial production - ready for assembly with no secondary processing required.
“Many car parts are painted, not just metal and thermoplastic exterior parts, but also thermoplastic parts in a vehicle’s interior,” said Gary Fielding, vice president and general manager, Color and Additives EMEA at PolyOne. “We have successfully helped carmakers transition from paint to MIC for many exterior applications such as skid plates and trims. This recent project is a significant step forward in reducing the cost to manufacture highly visible interior applications.”
Using metallic-effect masterbatches significantly lower the cost per part compared to paint or chrome plating – by 30% or more, according to PolyOne. Lowered energy requirements versus painting and the reduction of VOCs also make this masterbatch a more environmentally sustainable solution.
In addition, with the use of hexavalent chromium in traditional hard chrome plating under tremendous pressure due to concerns about its carcinogenicity, and the fact that its alternative, trivalent chromium (Cr(III)) does not always provide the desired effect, metallic effect masterbatches, say some OEMs, may be the way forward.
The challenge with masterbatch remains moulding parts that do not have visual defects such as flow or weld lines. The key to moulding good parts is for OEMs to decide, very early, that a part will be coloured with moulded-in colour masterbatch; that decision will then support the development of a mould and part suitable for masterbatch. Preferably, such a design would, for example, not have multiple holes or sharp curves in a part.
And though the argument against masterbatch always is about these visual defects, little is said about scrap from paint lines, which can be 20% or even higher, report OEMs. Hence painting is not only more costly, and energy-intensive; it also has very high levels of non-recyclable scrap.
PolyOne’s metallic-effect masterbatches can be incorporated into pre-coloured compounds or dosed at a moulding machine.