Tuesday, February 15, 2011

Digital Diecutting

Written By Mark Batson Baril

What is Digital Diecutting?

Digital Diecutting is the Buzz word for the converting of materials, that have been traditionally cut using dies, without the use of dies. Just like in the printing industries, where many short run prototype and specialty jobs have gone to digital printing, specialty diecutting projects are moving more and more towards cutting without a die.

Depending on the material, the shape to be cut, and the quantity to be cut, there are a variety of machines that can be used to cut products without tooling. Digitally controlled Waterjets, Lasers, Routers, Milling Machines, Drills, Specialty Cutting Knives, and even Ultra Sonic Waves are all used throughout the world today and all fall into the category of “Digital Diecutters.”

As this technology has become more sophisticated and controllable, great amounts of time have been poured into making these machines as fast as possible. Multiple cutting heads and beefed up construction techniques have made some of these machines faster and more economical than the traditional diecutting press, given the right situation.

Keep in mind that given the right quantities, nothing beats diecutting for speed! However, there are many instances where a projects production costs may be reduced by eliminating tooling, at least in the early stages of product developement. We recommend having a professional estimate costs using several possible production methods before a decsion is made.

Waterjet Cutting Gasket vs. Diecutting

Written By Mark Batson Baril

Waterjet Cutting Gaskets may be a better answer than die cutting.

"Given A Diecuttable Product In Production Quantities - No Other Cutting Method Can Beat Diecutting For Processing Speed."

Here's a quick one from a friend in NJ. He recently called seeking out a little relief from the mighty jamb he had gotten himself into with a good customer. It would seem that the drawing that was first sent on over to be looked at and quoted upon had been blown up to about four times its' actual size so the engineer could see all those fine nooks and crannies. Well, when the actual order came in for the 100,000 gaskets, the dimensioning was full and complete and revealed that the looming Christmas season may be a little more stressful than usual this year. Here's how it all went down.

The Question:
Please check out the attached drawing of a gasket product we just realized is perhaps too tough for a steel rule die. Can you suggest another type of tool or punch, or anything that will get the job done for us? "We're in a pinch and could use some relief" (I believe those were the exact words used.)

The Answers:
Some of the details of the fax that followed showed us a smallish gasket about 1.000" x 2.000" (25.4mm x 50.8mm) with a few small ovals, a few round cutouts, and four incredibly tight dog bone style cut outs that just about filled the image with clutter. The dog bone shape had a narrow slot to it that curved and the width of that slot was a mere .050" (1.27mm) wide. The kicker was this - the material is a specialty, ground to thickness, material in about a 65 durometer (pretty non-squishy stuff) in a finished thickness of .065"(1.65mm). Bingo! Very quickly the thinking started to shift. Steel rule dies and specialty punches were immediately ruled out. Cutting would be tough, and ejection would be even harder. They'd blow up a few thousand dollars worth of these tools and we would get taken off this guys Christmas list real fast. Male/Female tooling with a progressive design may accomplish the task but it was still risky since the other thing that wasn't on the original print or on the fax sent to us was the tolerancing. Yep... ±.005"(.127mm) on the finished part for all dimensioning! This is a really tough part to cut!

We started to explore the waterjet end of our industry for the short haul while at the same time our stressed-out inquirer explored specialty molding for the long haul. Sample cuts were made on the waterjet and the results were fantastic. Tolerances could be held and perfect nesting eliminated the amount of waste that would have typically been produced during a normal punch and feed. So now the trick was to get the pricing close to where the job had been quoted originally. Maybe to save face the diecutter would loose a bit of money or perhaps if the customer were understanding, there could be some room for upward movement in the price. I didn't think the diecutting price could be matched with waterjet cutting and once again the basic rule was proved. The rule of thumb on pricing diecutting vs. other cutting methods is this: Given a diecuttable product in production quantities - no other cutting method can beat diecutting for processing speed.

We did have several things working in our "Save Face for the Customer" favor, however.
  • The parts were going to be close to impossible to produce well on any type of cutting die. This was going to be a tough one for any diecutter to handle.
  • The Waterjet process will use less material to produce the same number of parts and that's great on this particular job because this material is pricey.
  • Partial deliveries were due on this job and partials could be produced without tooling, almost immediately.

So to make a long drawn-out process seem a bit shorter - A manufacturer was found that waterjet cuts using a four head machine. Processing speed got better by four times compared to the prototype run and although the price was higher than diecutting, and unfortunately higher than the base quote, the job dropped back into the producible realm. This dropped the stress level back into a manageable level and kept a few purchasing agents happy for a while. The larger batch of yearly parts will more than likely go to some type of a molding process to save money, but in the short run the problem was solved. This fix will also afford a bit of time to explore male/female tooling that has what we feel is a remote possibility of being the best method.

Wednesday, January 12, 2011

Progressive Cutting Tools

Written By Mark Batson Baril

What is a "Progressive Cutting Tool" and should everyone be using this type of tooling in their diecutting operation?

There are many different types of tooling for many different specialty applications that involve diecutting. Progressive cutting tools typically fall into the category of male/female or matched metal tooling. They can also include steel rule die or milled punch shapes as well. For the sake of this answer we are talking about a single tool where all of the component cuts are made within this one tool. What this type of tool does so well is cut very complicated shapes from difficult to process materials (AKA - the stuff nobody wants to work with). The shape will often include interior knock-out, slits, embosses, and unusually shaped perimeter cuts. Because the tool would be very difficult to build as a one stage, one strike does it all type of tool, the final shape is accomplished through a series of steps that the material progresses through. As to whether or not everyone should be using this type of tooling - the answer lies in the complexity of the shapes you tend to cut and whether or not you have the type of machinery, designers, and tool makers to run a tool like this.

The Machine:
The typical machine that runs a progressive tool is a punch press or a flatbed platen type press with some type of accurate incremental feed system. The key to having all your options open during the tool design phase is to have a machine that has an open bottom or clearing bolster plate, an open back or side(s) for clearing waste and feeding, and a feed system that is tied directly to the motion of the machine. For moderately to large tolerances (± .062" 1.57mm) the feed system must hold the material accurately the entire time it is in motion and while it is stopped. In this type of tool there is no registration while in the tool except for side guides. For more accurate alignment throughout the process (±.005" .127mm) the feed unit must hold and place the material accurately and then just as the impression is made the feed unit must allow the material to move freely and settle on the pre-punched locating holes (pilots). Having a finely tuned feed unit with a material release is critical to the entire process.

The Tool:
The typical tool layout will have a series of stages where various cuts take place. The natural stages occur in this progression -
    1. The material enters the tool and the first impression cuts a series of two or four pilot holes that will allow for exact registration during the balance of the cuts. The more piloting holes you have the more accurate the product will be. The pilot holes make the location by sliding onto or being centered by a tapered male pin in each stage of the tool. Other part related holes, shapes or slits can also be cut at this point. 2. During the second, third, or fourth stage(s), other cuts, embosses, etc…, can be made all in perfect registration using the pilot holes. The real beauty of the cuts made during the several progressive stages of cutting is that extremely unusual or complex shapes can be made via multiple cuts at one image. 3. During the last stage, the final perimeter cut is made and the final finished part is typically blanked through the tool into the part collector below. Because of the way the stages have been planned, the final part will have no chance of nicks or uncut areas in any of the normal joint areas related to a steel rule die.

During all the cutting, the material web is never asked to carry a part that has been pushed back into the web after a cut as is often the case with a steel rule or combo male-female/steel rule die. Each cut stage strips the waste away and only during the final cut does the web become weakened by the missing part. Because of this, the press can be run at maximum speed and accurate parts can be delivered waste free very quickly given just about any material type or part shape.

All in all this type of tool should win the "REALLY COOL TOOL AWARD".
This is one of those great areas to explore with just the right project and I hope that one day you have the need to buy, help plan, or run one in your shop too.