Find the keys that drive in-vehicle color harmony

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  • How to avoid color harmony issues in automotive interiors
  • Understand the challenges
  • Finding color harmony
  • Brett Conway, Group Director, Plastics, Americhem

Were you to picture buying your dream car, what sort of factors would be most important to you? Powerful mechanical components that make it fun to drive? Loaded electronics that improve comfort and entertainment? A slick exterior design? The best safety equipment? Good use of interior space?

How about the extent to which colors match inside the vehicle?

If you were an average consumer (and not someone working in the automotive polymers field), in-vehicle color harmony would probably never cross your mind. If, however, you sat in a new car and noticed the colors of the seat covers or console components didn’t match, chances are you wouldn’t buy it.

In-vehicle color harmony is easy to overlook until there is a problem—then it becomes of significant importance to consumers and OEMs alike. Vehicles are relatively substantial purchases, and in-vehicle color harmony is crucial to creating perceptions of high quality for buyers.

While important, creating in-vehicle color harmony is no simple feat. From challenges on the material level to process decisions that drive which parts end up in a vehicle, there is plenty of room for error. The more you know about where these potential challenges lie, the more likely it is that everyone ends up with an aesthetically pleasing final product.

Understand the challenges

There are many reasons a color mismatch can occur by the time a part makes it into a vehicle, with complications originating from material choices, processes and the many stakeholders involved. Specifically, challenges occur because…

A lot of parts make up a vehicle’s interior.
Hundreds of different parts must often match to some degree inside a single vehicle. Examples include the overhead console, steering wheel, instrument panel, interior trim, center console, floor carpeting, scuff plates, headliner, grab bar, glove box, interior door panel, radio trim and seat fabric… the list goes on. With many components making direct contact with one another, a poor color match may become obvious.

Parts are not all made of the same material.
There is significant variance in the material types found inside a vehicle. Filled and unfilled olefins, numerous engineered resins and other materials comprise a vehicle’s interior, with percentages depending on the vehicle model and region of the world in which it is constructed.

Parts are produced all over the world.
Not only must color match across materials, but across manufacturing processes and geographies, too. Especially in the automotive market, there is wide variance in where and how parts are constructed globally. The extent to which certain resins are used can vary on the local level, and processes may not be the same from region to region, even within the same supplier companies. As a result, color discrepancies can occur.

Measuring the color of these parts is complicated.
Instrumental assessment is important to color harmony, but it is not recommended to be the final word in product design. We can measure with instruments, but from material to material we see differences in grain, gloss, refractive index, texture and other traits that can undermine color measurement. Inconsistency between different color measurement tools also creates a risk of failure.

There are a lot of players involved in part creation.
For every OEM program that is orchestrated, there are typically several “tier one” injection molders and suppliers involved, each of which deals with several subcontractors that mold various modules, and each of those molders may work with several different colorant providers. The result? A lot of opportunities for color inconsistency—especially since color sourcing is typically not done from the top down in this process.

The color approval process can be complicated.
In many OEM supplier application processes, the individuals judging color harmony are not the same as the initial approvers of materials. Injection molders might be approved by an OEM to supply certain parts, but they might have to make tweaks to the product further down the line, as color harmony approval is a separate process.

How to avoid color harmony issues

With all of these challenges, what can be done? Take heart—there are a few steps that can be taken to mitigate the likelihood of a color mismatch inside the vehicle.

1. Consolidate partners, working with the best.
Given the complexity of OEM approval processes and the many different types of parts a molder may provide, consolidating the number of masterbatch and resin suppliers with whom the molder works can result in major efficiencies. Look for partners with:

  • Experience with Many Materials: Find partners with substantial experience working with a breadth of polymers, as they will have the best grasp on how color will appear in those materials—how refractive index, gloss or grain might influence color perception, for instance—and how those materials will fare in specific end-use applications.
  • Extensive Color Expertise: Look for partners who understand color well—how color theory should play into decisions, how to create a desired color in specific materials or how certain characteristics of pigments might stop metamerism between different materials, for example.
  • Consistent Operations: Look for partners with strong manufacturing process controls and consistency with facilities across many geographic locations. Global parts availability is a major benefit, too. This is not only a sign of a well-organized company, but gives you the best opportunity to avoid variance wherever possible.

The more injection molders can consolidate operations and work with fewer, knowledgeable partners on more programs, the more likely they are to save time and reduce costs related to additional trials, resubmission of parts and changes during color harmony reviews.

2. Consider every part of the process where color might be affected.
Regardless of how many suppliers are involved in the process of creating automotive parts, there are enough steps involved in the process that color could go awry at numerous points. Think about how processes might be streamlined and monitoring of color consistency can be integrated into the following stages:

  • Masterbatch development
  • Resin formulation
  • Injection molding of part (especially complex)
  • Finishing of interior automotive part
  • Installation of the part into the vehicle

If parts are not ending up the color they were intended to be, it isn’t necessarily the pigment that is the problem. There could be something occurring during any of the phases above that is causing a color deviation. An experienced color supplier can help work through these challenges.

3. Use color control protocols to control physical standards and ensure good color tolerances.
Besides limiting opportunities for variance by consolidating partners and looking more comprehensively at the in-vehicle component creation process, there may be improvements to the way color is being analyzed that can help maximize the success rate of color harmony approvals and minimize costs.

Visual assessment is important, since any future driver of a vehicle will be judging color harmony with their eyes, not a spectrophotometer. It is also extremely subjective, as color vision deficiencies, mood, lighting or even social pressure can affect perceptions of whether a color is acceptable or not. Instruments are less subjective, but they often are affected by differing refractive indices, gloss, grains, textures and shapes… especially between different material types. There may always be challenges here, but there are a few steps to take to compensate.

Use various standards to guide part creation.
Create an Official Standard comprised of a specific material (such as polypropylene) to physically represent the visual and instrumental target of all parts associated with the concept color. Create Reference Standards that are physical standards composed of each material that will be used for final parts (polypropylene, ABS and PC-ABS, for instance), and which are measured against the Official Standard to ensure the same spectral curve and character exists. Finally, create Working Standards based on the Reference Standards that can be used in day-to-day operations and replaced when they become soiled.

Protect the integrity of your standards.
Because of the issues with differing material refractive indices, grains and glosses, Reference Standards will need to be calibrated visually to the Official Standard. Observations should be done under multiple calibrated light sources to ensure a non-metameric match by approved observers tested for color vision deficiencies. Once approved, the Reference Standard should be stored in an acid-free opaque sleeve and handled with clean lint-free gloves The Reference Standard should be measured and saved to measure later to determine if it has been soiled. Meanwhile, the Official Standard should remain safely stored and only used for creation of other standards.

Determine color acceptability using an elliptical pass/fail system.
Creating an exact match between two colors with no visual differences is both difficult and expensive, thus you will always have some degree of variance within which part color should be deemed “close enough” to be acceptable to both OEMs and consumers. There are different ways to determine tolerances, including box, circle and elliptical systems, but the latter gives you the best point of reference when determining a tolerance that accurately reflects whether a batch of color polymers will be visually acceptable as it accounts for the realities of how humans view color by allowing customizable emphasis on chromaticity and hue. This system, developed by the Color Manufacturing Council, gives you the best probability of avoiding false negatives and false positives during measurement, which in turn minimizes your chance of making costly mistakes. Some instruments are calibrated to calculate according to the CMC (l:c) equation used to create pass/fail ellipses, but you can also look up and run the calculations yourself if necessary.

Finding color harmony

If you are seeking color harmony inside a vehicle, you have a lot working against you. It doesn’t mean color harmony is impossible to achieve, however—it is done successfully thousands of times per day. The key is knowing where things can go wrong, why and how to put the best color control protocols in place to maximize your likelihood of approval the first time. Know the basics, and work with experienced partners and you will be best positions to lower your overall costs while delivering quality results.

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