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A Guide to the Cost of Failed Masking in Finishing Processes

Posted on Tuesday, October 29, 2019

A rack of discards sat in the middle of the room. Shelves of streaked parts, awaiting their disposal. “What happened?” we asked. “Oh, the plugs must have leaked as they were coated,” was the reply. “We discussed whether rework is an option, but in the end, it’s cheaper to just scrap them rather than strip and start over. That’s why we called you,” they sighed.

Masking can fail for several reasons:

·        The mask is not correct for the process being used.
·        The mask is not sized properly.
·        The mask has reached its end of life.

Part I – Yes, You Could Do It That Way
Often when our team members are on-site with large customers, we are presented with opportunities in new departments or on different production lines. We hear, “It’s what we had on hand and it worked…kinda.” Sometimes having masking experts take a look can be a game changer.

For a recent customer, we saw a very cumbersome, mechanical masking solution being utilized. It required a bit of finessing to insert, the use of an impact wrench to apply, and a tremendous amount of torque for it to expand and fill the void. Unfortunately, this pressure quickly overcame the structural integrity of the rubber mask, greatly reducing its life cycle. This reduced life cycle required each mask to be replaced each month at a cost of $75 per piece. Perhaps that would have been acceptable – but there was still a 30% failure rate! Certainly, there had to be a better solution.

Enter CFS and our custom masking capabilities. We were able to use our patent pending vent plug, which acts as a one-way valve – easy to apply and non-leaking. The CFS solution reduced application time 75%, saved 50% on the masking costs, extended the life expectancy of the mask and virtually eliminated rework.

We encourage companies to contact us with the tough problems. The solution may be eliminating hand trimming tape by using die cuts, swapping out the style of masking, or even creating a completely custom solution. CFS can help your productivity and bottom line.

Part II – Close, but No Cigar
A new vehicle cab rolls down an e-coat line with 65 threaded holes which needed to be masked. A call is placed by a purchasing agent to a supplier that sells masking plugs. The size of the holes is relayed to the supplier who sends a variety of masking solutions for the holes in each part. Sounds simple right?

Not so fast… CFS was invited to evaluate why the current supplier’s plugs had failed - causing extensive tapping of all threaded holes after being coated. We quickly determined that the masking did not fit properly. Some were too small, others too big. The original supplier did not properly consider all the factors surrounding e-coating – namely immersion and pressure.

By the time we intervened, this had been happening for many, many months. It was assumed that chasing out fouled threads was the best method available. As scrapping the part was not an option, rework was the only solution for this manufacturer.  Not only did CFS solve the issue with one site visit, CFS also saved the customer over $10,000 per week in combined labor costs and masking products!

We pride ourselves on being far more than a catalog order company. We believe in taking a consultative approach to your business. By learning your manufacturing procedures, we can become a partner with you in your finishing processes. We have five locations staffed with masking and finishing experts ready to lend their expertise to your most challenging issues!

Part III – Penny Wise but Pound Foolish
Walking through manufacturing plants and coating operations, we often see the same sight. Buckets, bins and shelves full of used caps and plugs covered in coating, torn and deformed from overuse. While it is true that these plugs and caps are designed for reusability, they do have a shelf life. When used past this point, issues can quickly mount.

Although most coatings don’t adhere to silicone, over time repeated bake cycles will cause both silicone and EPDM rubber to dry out. As this happens, caps and plugs become less pliable, crack, craze (to produce minute cracks on the surface) and build up coating with each new use. Once this happens, plugs will not seal properly, and caps will begin to tear and leak.

Some coatings involve the use of chemicals. Some of which can be caustic and can greatly reduce the life span of any rubber materials used for masking. In some cases, caps and plugs may become very soft, deform and tear. Depending on the chemicals and processes, this could take many cycles before it becomes a problem – or it could be just one. This is why it is so important to test and establish life cycles for all silicone and EPDM masking caps and plugs.

When these products reach their end of life, they need to be replaced for the integrity of your finishing operation. For high volume processes that require multiple plugs per piece or large custom masks, those in charge of the purse strings may want to push the limit for this lifespan. However, using the example at the beginning of this article – how many tapered plugs can a company purchase for the loss of one part? How many plugs add up to the cost of chasing coatings out of threaded holes?

Our team at CFS will gladly send free samples for testing and work with your process engineers or finishing departments to determine the best replacement schedule for your masking parts. It can be as easy as putting a procedure in place to replace masking on a set schedule – say the first production day of the month.  In other cases, we can make recommendations to increase the number of cycles a custom mask can endure and suggest testing criterion.

CFS has over 40 years of experience in the industry and are experts in surface protection applications such as tapes, plugs, seals, mounting & holding, gaskets, spacers, shielding and insulators.  Our capabilities include precision rotary die cutting, dieless knife cutting, kiss cutting, custom rubber molding, slitting and laminating. Masking experts are available to consult with your paint line supervisor, production manager or lean manufacturing engineers. Give Custom Fabricating & Supplies a call today or visit us online to read more about our extensive capabilities!