Everyone approaches scrap in a different way. Reducing it can be complicated by your own internal processes, and the nature of the run. But are there some fundamental, surefire ways to reduce scrap?
We tapped into the insights of a number of experts in manufacturing and included their thoughts on best practices for reducing scrap. Here are nine suggestions:
1. Improve your training
Mike Lynch, Founder and President of CNC Concepts, notes that “most of what causes scrap workpieces can be traced to human error.” Not surprisingly, these issues are typically tied to training.
At Delta ModTech, many of our machines’ complex converting processes are handled by software applications. But if these programs aren’t operated correctly, and the machines aren’t used as they were designed, scrap is the natural byproduct.
As USA Marlin notes, a well-trained team “will make smarter use of resources, and not have to go through nearly as many ‘trial and error’ experiences to find out what does and does not work.”
2. Choose the right raw materials and engineer them well
As materials become increasingly more sophisticated and multi-functional, the cost of scrap rises as well.
For example, Action, a converter that specializes in the automotive industry, manufacturers multi-layered stacks that combine a mirror with an LED light. The stacks require a light diffusion film, and the entire stack has extremely tight tolerances.
“Everything is getting smaller and more powerful,” said Scott Anderson of Action. “And as a result, more expensive.” This amplifies the need for smart design and sophisticated machinery; the two must work hand-in-hand.
3. Conduct a cost AND a process analysis
If your process is already underway, you should consider a cost analysis of the current materials you’re using. Many times you can find materials that have the same performance properties as those on your current process but cost much less or can be rewound and reused (check out this post on the topic). This can be especially effective with sacrificial liners. But don’t stop there.
Take a look at the converting process you are using. For example, CSI Medical found that instead of running two separate runs for a multi-layered label, they could use an Island Transfer process to save even more costly materials and reduce scrap. The moral of the story: Always look for a better way.
4. Use closed-loop vision systems
We’ve blogged about the importance of automating changes on the fly. Too often, a converter’s process includes completing a run, then relying on their inspection team to flag the mistakes. This ties up staff resources, and creates runs with substantial scrap.
Yet spotting the “small motion mistakes” that occur during a run are difficult, as Mike Lynch notes.
A solution is a closed-loop vision system, in which cameras work closely with your software to automatically make adjustments during the run. Changes are made instantly, dramatically reducing scrap.
5. Minimize handling of cutting tools
The quality of your cutting tools has never been more important due to increasingly high tolerances. And the risk of human error occuring in the handling of these parts heightens the chance of nicks, scratches or defects.
You want to minimize the handling of your tooling as much possible. Opt for flexible cutting plates, and use cranes for the loading and unloading of large rotary dies. Of course, the ultimate hands-off approach is to use a laser-die cutting machine.
6. Stop removing scraps and slugs by hand
Your standard process may include removing scraps by hand. This manual process, particularly when used with rotary dies, can result in a number of issues.
For example, scrap that accumulates inside a die cavity can have a pressure buildup, which leads to blade fractures. Or scrap that accumulates between the anvil and contact surface of the rotary die can result in an uncut part.
Example of a slug removal vacuum.
By integrating automated slug removal into the process, you can more efficiently remove scrap from the moving web. For more details, check out our post “8 Ways to Make Scrap Removal More Efficient During the Rotary Die-Cutting Process.”
7. Create and maintain a bill of materials for each product
Documenting processes is a critical part of reducing scrap. Part of the documentation requires an improved bill of materials (BOM) that is both accurate and up to date. This is more of a dynamic list, which moves beyond the initial list created with the CAD drawings.
We detail this process in our post on quick changeover, including details on what should be included in your bill of materials.
It’s critical that all product data be “current and correct,” so that the product is always built to spec.
8. Reduce the number of prototypes by improving communication between design and production team
Concurrent Engineering points out that by “reducing the total number of physical prototypes, it can also reduce your production point.”
So how does that occur? It requires better coordination earlier in the development process between designers, the production team, and the materials supplier. When all of these parties communicate more effectively prior to the prototype stage, your risk of failure is greatly reduced.
According to Mark Cheatham, Vice President of Engineering at Strouse, “The real challenge is getting the product development team to understand the end goal.” The earlier the product development team is involved in the design, the faster they can point out troublesome production elements.
Mark Cheatham, Strouse
9. Avoid lag time in communicating changes
As you work to continually improve your manufacturing process and reduce scrap, you’re going to be making changes. Documenting those changes is half the game; you also need to communicate them quickly to all stakeholders.
As we’ve noted in this post on knowledge sharing, easier sharing of information and processes can impact line performance and reduce downtown. The company Poka “has seen some companies increase their OEE from 60 to 80%, and others who were already above 85% increase by 5-6%.”
The impact of scrap on any operation is wide-ranging, but with the escalating costs of materials, even the slightest improvements can lead to significant results. Consider these tactics as you’re evaluating your overall processes.