How to Avoid Common Press Set-Up Problems
Editor’s Note: This is the first in a series of articles about setting up an efficient die-cutting press system. The article includes excerpts from a transcript of a highly popular presentation at the 2007 Odyssey exposition made by Randy Norman, applications specialist at Preco.
Most die shops have the same material costs and virtually the same overhead costs; so where you make your money is improving your labor costs. If you can increase your efficiency when you’re setting up and running jobs, it will decrease your labor and increase your profit.
This article will highlight ways to avoid costly set-up problems.
Know your press system and what efficiencies it can provide.
It’s critical to know what type of system you’ve got and what the capabilities are of that system. If you want a kiss cut, certain machines will not be appropriate. I was talking with a gentleman who was trying to cut polycarbonate, and he was getting distortion of the part. He was using a swing beam press to kiss cut the part. The problem was his cutting pad was too soft. He should have been cutting onto a hardened surface or something harder than the substrate.
Make sure you know which press system will be used. Do you hand feed, or do you automatically feed? Is it sheet fed or web fed? Is it printed or unprinted? Do you have the ability to automate other operations like knocking out and stacking the parts, de-slugging the part, sheeting the web, slitting the web, laminating web to web or web to sheet? These things will reduce the amount of labor (and costs).
Order the proper tooling.
It’s also critical that you order the proper tooling for your press system. There are four primary factors that determine the type of tooling required:
1. Length of the job run.
Tooling will wear out depending on the number of parts you need produced and what material you are using. With a material such as sandpaper, for example, steel rule die tooling is good for about 8,000-10,000 hits before wearing out. A material such as Polypropylene is good for over 100K hits before the steel rule die needs to be re-ruled or replaced.
Although much more expensive than steel rule dies, Male/Female dies can achieve a life rating of over 1 million - 10 million hits (or more) per tool before re-sharpening, depending on types of materials cut.
2. Type of material being cut and type of cutting operation required.
When determining the type of material being cut, keep in mind whether it is a strip or sheet, printed or formed, embossed, debossed, scored, etc. How thick is the material? How wide is the material? Is it a single or multi-cavity tool? Is the material laminated?
The material characteristics are also important. Does static affect the material handling? How do parts react in the sheet once it is diecut? Is it coil or web? Is it printed or not? If you think about other variables, you’ve got different tooling types, such as steel rule dies, machined dies and etched dies. Heights of steel rule can vary, as well as the thickness of steel rule, not to mention the angle bevel of the knife, type of the rule edge, hardness of the steel rule, steel rule coatings, Teflon, titanium, special coatings, etc. You must also consider different types of dieboard, three quarter, jig cut, laser cut, 5/8" (15.87 mm) dieboard, nylon, and then different variables in cutting medium, like cutting on a nylon plate, spring steel, a hard cutting plate, or epoxy glass. What about the ejection rubber? Is it open cell, closed cell, spot rubber, full rubber, and what density?
Again, make sure you know what type of cutting operation is required: is it a kiss cut, cut through, combination tooling, score cut? Is there creasing and forming?
3. Accuracy or tolerance of the cut material.
The level of accuracy you wish to achieve is also critical in determining what type of tooling you need. Automotive dash overlays, for example, require higher cut-to-print tolerances due to high quality printing. The tolerance required is often +/-.001" cut to print. This cannot be obtained using a steel rule die. Typical tolerances of a steel rule die are +/-. 005" to +/- .010" so this tooling is not accurate enough to cut out the part tolerance dimensions let alone a printed part cut to registration. Another example would be the tolerances of a flexible circuit. Again, due to part tolerances specified by the manufacturer, steel rule dies cannot be made accurately enough for the overall part cut size.
4. Type of press being used.
There are many types of presses that run different types or multiple types of tooling: clamshell, hydraulic, mechanical, beam, clicker, and traveling head. Your diemaker must know the type of press you are running.
Get your diemaker involved in helping you order the proper tooling.
Twenty years ago when you asked a diemaker to make a tool, all he wanted was a drawing. That’s completely different now. Diemakers want to know what substrate is being used. They want to know how it handles. They want to know if it’s web or coil. Make sure your diemaker knows what process you’re performing and what type of press you’re running it on.
I had a customer who spent four days on a tool and he couldn’t get it to kiss cut. I went to his plant and discovered that the diemaker had actually welded pieces of steel rule together when he made the die. This caused the die to have an uneven surface making it impossible to kiss cut the material. I called the diemaker, and he came in and looked at the press and his tooling. The diemaker said, “Look around at all the other presses the customer has.” All the other presses, with the exception of the Preco press, diecut “into” a soft cutting pad. “Into” diecutting does not require a precision steel rule die. The diemaker was never told by the customer that they had purchased a Preco high precision press that cut “onto” a steel plate. The cost difference of a high precision kiss cut steel rule die was $5 more than the tool he had previously made. The diemaker made a new die the next day; it took me 15 minutes to set it up and kiss cut. The customer lost four days of production time to save $5 on a tool. Again, I can’t stress how important it is to communicate with your diemaker.