Why big international brands can’t get their print colors right every time. Color Material Finish (CMF) explained.

 

By Michael Schjerbeck, January 2021

Knowing what we know from DFMA – Designing for Manufacturing and Assembly the choice of Colors, Materials and Finishes (CMF) are a vital part of the product development process. Making these clear from an early point in time is essential to save time and money later on.

 

Materials and Finishes

Knowing if your product is to be made of plastic, metal, silicone, wood or other materials is absolutely necessary to determine as early as possible. It will have a lot do with the overall design process and how your product will function in various environments.

 

Each material has its advantages and disadvantages, so choosing the right material for your product will take some time and research.

The most commonly used external materials for consumer electronics are thermoplastics. With the most common of them being:

ABS / PP / PS / HDPE / Nylon / PC / TPU / Acrylic

 

All of the above materials require an investment in molds and tooling. But what type of material to choose when designing your products? For this you need work from the outside in and ask yourself some questions.

 

What surface finish is needed?

  • Plain Matt Color
  • High-Shine
  • Rubber / Silicone feel
  • Metal finish
  • Wooden look
  • Fabric
  • etc.

 

Then you need to specify what characteristics the material should have and where the product is used.

  • Medical
  • Food grade
  • High / Low Temperature
  • Impact resistant
  • Water resistant
  • (Non) Conducting etc

 

After having specified the above you should review each material available and see if it matches the finish and application you are looking for. I have made a table below on some of the most commonly used plastics for injection molding, that will explain what Finishes you can expect from which plastics. If you are in the medical sector or other highly regulated industries, other materials than standard thermoplastics might be required, which might have to be medical grade and contaminant resistant. Here choices of suppliers will be narrower due to needs of medical certifications and regulations imposed.

It is possible to mix some materials and add various other material such as glass fiber or flame retardants into your ABS or PC. Such mixes will change the characteristics of your part and your tool’s lifespan and injection cycle might decrease.


 

So how to relay the finish you want on your product to your supplier / tool maker?

For this there are some “international” brands / standards you can use.

 

YS (Yick Sang) finishes

From a high gloss finish to various textured patterns and specifications.

Mold-tech

Follows the same principles as YS, just with different reference points.

 

SPI finishes

Same as YS and Mold-tech but with less options and reference points.

With a few google searches you will be able to find these companies and order their swatch samples.

 

Remember to follow the rules about draft angles for injection molding for more textured (rough) finishes. The more texture the bigger the draft angle should be, in order for the tool to release the part without scratches.

 

Some surfaces might have part high-gloss and rest matt. This is only possible to make if you choose a material which characteristics allow for both finishes to appear nice.

 

Remember to discuss in details with your partner about the usage of your products and why each surface is chosen by you or your designer. Some surfaces require a 2nd treatment to stay pretty and scratch free for a long time.

 

Secondary treatments of plastics

“Water transfer printed plastic part”

 

Water transfer print

Water transfer printing is process that allows the plastic to be coated by a print film. Any pattern or colors can be designed with a minimum of two colors. Usually this is used for camouflage, fake carbon fiber, imitation wood surfaces and complex images.

 

Paints

  • Matt Paints in colors
  • Shiny Paints in color
  • Silver / Gold / Copper in matt to shiny
  • Rubber paint (This is NOT recommended to use). Rubber paint will after 2-3 years get sticky and rub off. There is no way around the fact that it’s a great paint to use to hide a poorly made tool or injection, but its lifespan is very short lived, leaving the consumer with a very ugly and rather nasty product after a couple of years. (see below)

Electroplating

Electroplating is a process where you make plastic look as if it’s a shiny metal part, by submerging the parts in to an electric charged bath that allows metal to bind to plastic by priming the plastic. The process requires a skilled factory and benchmark samples of the color you expect to reach. Making samples is expensive, and requires time. An electroplating factory will have to stop production and adjust the electroplating bath to your desired colors.

With more and more environmental focus in china most smaller electroplating factories are closed down, so this process has a much higher demand than supply. Waiting for up to 2 weeks for samples is quite normal.

 

UV coating

UV coating is process where a usually a clear coat of UV paint is sprayed on top of a painted plastic part. This part is then goes through a UV oven which binds the UV paint to the part, leaving it with a shiny and scratch resistant surface. This of course leaves you with a higher production cost, but might be suitable for high quality products.

 

Mix of Finishes

There are many ways to combine materials and finishes. Your product might consist of a mixture of multiple materials. It could be a consumer product which incorporates both plastics / aluminium and fabric surfaces. In such instances it’s best to find a company that is used to work with all type of materials and has experience in combining materials. In such cases there are many tolerances to consider.

 

Wood and Glass have a much higher tolerance than engineered plastic parts. Casted or hand polished metal parts will likewise have higher tolerances than CNCed and machine polished parts.

 

Gluing fabrics to plastic parts in combination with an aluminium casted top might however work, since the fabric is flexible and might hide some tolerance deficiencies, making the product look even all around. Here the choice of fabric is just as important, since a stretchable fabric will be more forgiving than a ridged one.

 

Let’s take a look at what other materials you can choose from for your consumer product.

 

Silicone (Various)

  • LSR (Liquid Silicone Rubber)
  • FSR (Fluorosilicone)
  • HCR (High Consistency Rubber)
  • RTV (Room Temperature Vulcanization Silicone)
  • HTV (High Temperature Vulcanization Silicone
  • Optical clear silicones

Rubbers

  • Chloroprene rubber
  • Butyl rubber
  • EPDM
  • Epichlorohydrin
  • Fluoroelastomers
  • Hydrogenated nitrile rubber
  • Chlorosulphonated polyethylene
  • Kalrez®
  • Nitrile rubber
  • Perfluoroelastomers
  • Polyacrylic
  • Polyurethane
  • SBR
  • Vulcanized rubber

TPE/R (Thermoplastic elastomers/rubber) usually used for overmolding

  • TPE-S (Styrenic block copolymer)
  • TPE-O (Thermoplastic Olefinic elastomer)
  • TPE-U (Thermoplastic polyurethane)
  • TPE-A (Thermoplastic Amide Elastomer)

Fabrics

  • Polyester
  • Nylon
  • Neoprene
  • Cottons etc

Wood (define your finish and application needs)

  • MDF
  • Real wood (all sorts)
  • Fake wood finishes etc

Metals (define your hardness and application needs)

  • Aluminium
  • Stainless steel
  • Copper
  • Brass
  • Iron etc

Glass

  • Natural glass
  • Painted glass
  • Crystal etc

 Packaging plastics

  • PET (Polyethylene Terephthalate)
  • PVC (Polyvinyl Chloride)
  • PS (Polystyrene)

All of the above materials have unique characteristics and each single material require an in-depth article, and it would probably bore you to sleep reading about of them. So let’s move on to colors.

 

Colors

How often have you received a product and thought – hey that’s not exactly like the picture i saw on the packaging? Probably not very often. But companies go through a great deal of trouble to stay as true as possible to their initial design and preset colors.

 

Many start up companies and in-experienced product developers give very little thought to how difficult or easy it is to match colors.

 

So how do companies make sure their product and packaging colors are exactly the same from samples to mass production batch to the next batch. To be quite frank, almost no-one can. Very very few companies have the skills, the quantities and the resources to ensure each batch being the same.

 

Just compare your credit cards. If you have two Mastercards from different banks, the chance that both bank’s printers printed the mastercard logo with the exact same color is slim to non. Both are close but not 100% on point. Here are the reasons why.

 

In order to reproduce a color perfectly accurate every time, the conditions would have to be the exact same for each time a part is printed, sprayed, injected, electroplated etc. From temperature and humidity to brand of raw material, nozzlehead, inkjet, toner level, product surface, placement in bath and material composition down to drying time and thickness of paint. Many surface treatment are carried out by hand and materials and environments vary -therefore variations will occur. (and sometimes is just carelessness).

So how do you get close to your desired color?

 

Pantone: Use and invest in pantone color books. Pantone Colour is a proprietary color space used primarily in printing, paints, fabric, and plastics. Pantone(R) is constantly developing new colors to their selection and probably the most used color reference we have. Pantone also provides a printing mixture of base colors.

 

RAL. Ral is your second option, which is a colour matching system used in Europe. RAL Colour matching system comprises 420 solid colors and seventy metallic colors. RAL color swatch book are rarely used in China and have no reference points to the base colors used by RAL.

Pantone colors are widely used in China and most manufacturers have a Pantone book – HOWEVER the pantone book might be several years old and yes i’ve seen many faded and heavily used pantone books during my two decades here. So here is your next obstacle – “does my supplier have a pantone book that is up to date with non-faded pages?”

This is why Pantone developed real swatch books. Meaning you can actually send a small swatch of color to your partner and ask them to match that as close as possible. Other tools such as digital color readers are available from various brands. With built in optical light sensors they can give a feedback on their built in LCD screens about any surface’s color. This is a great tool compare an approved samples vs. new batches, but not foolproof.

Matching colors cross various materials is even more difficult. Since each material composition and surface structure are different, even you would spray paint them with the same paint, they would turn out different. Sometimes “close enough” is perfect in this imperfect world.

Always try to approve an acceptable color range with the middle being the optimal color -+ a few % and don’t allow your partner to produce the next batch based on the previous batch, since you then might move too far away from the original color without noticing it right away.

If your original color was at, let’s say 10, and your acceptable color variation is set to 5% for the sake of demonstration. Then if your second batch was at 10.5 which is just acceptable, your next batch might go to 11.025 and still be acceptable if you allow your supplier to produce based on the previous batch color. You should therefor only refer to colors based on your first approved “Golden samples”.

 

Final thoughts

Try to define your surfaces, materials and colors as early as possible. Make a CMF specification drawing that highlights all your materials, colors and finishes you wish to achieve. This step should be a collaboration between the designer, you and your development partners. If only a 3D rendering is made and these specifications are not specified – discussed and confirmed some quite serious misunderstanding might lead to headaches along the way. Your development partner might quote on something completely different than what you expect. By discussing these things, including a definition of each part’s surface treatments from an early point you eliminate problems happening later on. It is worth to study and do some research prior to starting a new product development.

 

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Above was just a brief introduction to the challenging world of CMF to consider when designing a new electronic consumer product. In my next articles I will address the following points: Locking parts in place / Getting quotations / Getting tooling quotations / The importance of Packaging and Manual making / Traceability / Markings and label / Assembly costs / Pilot run / Cost down solutions / Certifications / Mass productions / Quality Assurance and Quality Control / Logistics / RMA procedures / Long term partnerships and contracts / Resource allocations / Specific details when developing connected products / Specific Details when Developing Audio Products

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