Ch13. Unwrapping CMF Design on Sample Signing

A few months ago, just as I was wrapping up at the job, I received a farewell gift from the designers, which came with a handmade card made of what we use everyday at work: CMF approval stickers. (中文版)

I learnt about the usage of the stickers from my previous company and brought it to Motorola. It is useful in a way to make the signature more visible and the signing process more efficient. Although it is not a tool for every company, the duty of sample sign-off is however a “must-do” for most CMF designers, as well as for many industrial designers.

CMF is a specific discipline within industrial design that focuses on the development of a product’s color, material, and finish. Unwrap CMF shares bite-sized stories of CMF Design to inform and inspire those interested in this niche yet fascinating field, with digestible contents for anyone and everyone.

Sample sign-off is a process where designers decide an acceptable limit range from the trial production. This limit range will be neatly arranged in a CMF limit board by the supplier, and used for the control of color difference and other CMF details.

Sample sign-off: The process of signing samples.
Golden sample: The most ideal sample.
Limit sample: A sample that is close to the golden sample with a slight deviation but can be accepted.
Limit range: As above, plural.
Limit board: As above, plural and arranged in a booklet.

Why is limit range needed? In actual mass production, it is impossible to achieve the exact same state as the golden sample, so it is necessary to define an acceptable range. The narrower the range, the lower the yield rate. It means more samples are excluded, leading to higher production costs, and slowing down the production speed.

Therefore, while paying attention to the color coordination between parts, designers also need to balance the trade-off between golden samples and yield rate, and define a reasonable CMF limit range.

A sample of our approval sticker at Motorola/Lenovo. My team used the stickers as a cute farewell card for me, so please don’t take the hand-written content in this photo as reference.

When suppliers provide a limit range, limit samples shall be neatly arranged in a CMF limit board as shown in photo.

Limit samples in a limit board are arranged in order, such as from dark to light, from glossy to matte, and etc.

Though extremely unnoticeable for most people, designers need to carefully control limit range to reduce color gap in production.

Enjoy learning? Use the CMF terminologies mentioned above and continue on with your own research journey on the web. Comments and inspirations are welcome!
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