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.

Wednesday, December 29, 2010

Cutting Registration to Printed Fabric Materials

Written By Mark Batson Baril

A brief question:
I am in the promotional product's business. Currently I am preparing to manufacture a product where I will need to cut sheets of fabric, such as neoprene and ultraseude (polyurethane) into (140) 3 inch (76.2mm) X 1/2 inch (12.7mm) printed strips. I have contacted various die cutting facilities but there are potential accuracy problems since the sheets may not be perfectly shaped and may not align perfectly. I am assuming that some form of laser guided cutting would illiminate this concern?

And a brief answer:
Right off the bat I can think of a few ways to approach the project you are talking about. The fact that your printing may wander and not be in accurate/consistent registration to any corner of the sheet is the main problem.

Registration marks could be printed at the same time as your main printing. These could be designed as either simple slash marks or simple target type circles. This then opens up your options.

    1. Use the registration marks to align your materials in any type of cutting machine. Diecutting, guillotine, and laser immediately come to mind. A simple retractable and clear overlay that has been pre-struck acts as your line-up. Each individual sheet of material to be cut is lined up under the retractable sheet. Once the part is aligned and fixed to the cutting bed the clear overlay is moved away and the impression is made for a near perfect cut every time. 2. Other tooling methods would include using see through tools that could be registered one at a time on press by the operator. A clear Polycarbonate (*Lexan) or Acrylic based steel rule die or clicker type die may be your best bet. 3. Circle type registration marks can be used with a *Spartanics type machine that will automatically pre-punch a perfect hole at the mark. This can then be used in conjunction with a tool that has retractable registration pins. This method is used all the time in the membrane switch and flex-circuit industry.Optical registration is also an option on many diecutting machines and may be a good method for your particular job.

Each of these methods will result in accuracy of ± .010"-.015" (.254mm) depending on the operator. These ideas are slow but luckily your quantities are small. If you increase your quantities you will have to inquire about better ways to register to the flexible material you are using.

Wednesday, December 15, 2010

Rotary Steel Rule Diecutting Hard Anvil

Written By Mark Batson Baril

I recently read a press release that said that a rotary steel rule die could be used cutting against a hard steel anvil. I thought that you could only cut into a soft blanket with this type of die? Could you give a brief explanation of the benefits vs. soft anvil, differences in the tool/press, make-ready differences or comparisons to flatbed steel-on-steel and anything else that could clue me into this new technology? Is it new technology?

This is not new technology. It has been around at least 20 years. Marumatsu Company manufactured a 1350mm & 1700mm (53" & 67") diameter bottom cutter with a stripping section. United Machine has also made a 1.700mm (66") S-S top cutter with a stripping section.

The die is built in some ways similar to a flat die with extra considerations such as the straight rule is always mitered to curved and curved cut pieces are usually no longer than 10 inches. Soft anvil rule is serrated in order to penetrate the urethane blanket where as the S–S rule is a continuous bevel (non-serrated). The rule used in S-S cutting is 4pt center bevel edge hardened with a soft base. The idea here is to run-the-rule-in so that it levels itself off before actual diecutting begins. Rule heights around the cylinder vs. across the cylinder are varied by about ,075mm to ,127mm (.003" to .005") and the final heights are established during the run-in process on press. The hard anvil cutting surface is made out of an 85+ Rockwell steel and stands up to a great deal of pressure. As you can imagine, much of the success you achieve with this process comes from good maintenance of the press and well made and maintained tooling. The rule must be consistently perpendicular to the base surface and that tool base material must be able to maintain a perfect curvature. Excellent tool building and on-press “tricks” account for the success or failure of this process.

The benefits over soft anvil rotary cutting are that you can achieve the same rotary speed with the accuracy and cut quality of flat-bed diecutting. Because the surface you are cutting against is consistent, you avoid the dimensional variance that you get during soft anvil diecutting. Recent improvements in blanket re-surfacing and tool calibration to the soft cutting surface during prodcution have improved finished part tolerances, however there is still a big difference between the two processes.

Typically a stripping blanket is manufactured with each cutting die. The blanket is made from a ,75mm (.030") mounting material with "T" and "L" shaped stripping pieces attached to push off scrap in a section immediately after diecutting.

Because the cylinders run 1:1 in their gearing (opposite to a soft anvil cutting where the soft blanket cylinder will strike the cutting blades in a different spot every turn), the make-ready process can be made in several ways. Upon running the die and beginning the diecutting process and after achieving 80 percent good cutting, make-ready tape is applied to the die cut anvil in the non-cutting areas. This raises the substrate and helps the cutting in the non-cutting areas. Some companies will also make-ready under the die for fine tuning. This is typically the wrong way to go when making ready in flatbed applications but because there is no secondary steel cutting plate on top of the cutting cylinder, behind the die may be the only choice. The tricks here are in choosing a rule that will self-level and having an operator that is level headed enough to make it self-level. The 1:1 gearing/cylinder ratio also lends itself well to using matrix or other counter materials to form the scores.

From what we can see out there, this process seems to be a fairly rare one. Not many presses were made with this capability and the tricks of the trade needed to be successful seem to have taken a toll on its popularity. The companies that are using steel to steel rotary with SRD’s are enjoying some terrific benefits!

Some of the stories that helped answer this question and put together this summary were told by;

  • Thomas A. Sporleder – Printron

  • Mike Porter – The Rayner Company

  • Tommy Moore – Stafford Cutting Dies

    Thanks Guys!

  • Wednesday, December 1, 2010

    Laser Cutting

    Written By Mark Batson Baril

    (LASER) Light Amplification by Stimulated Emission of Radiation

    Lasers come in many different shapes and sizes. They range in usage from the standard supermarket scanner to those being developed as part of military defensive systems. The laser has existed in usable form since the mid 1960's.

    The type used almost exclusively for cutting a wide range of materials is the CO2 gas laser. Hole drilling is typically done with solid state YAG lasers.

    A laser beam is created by the introduction of gas and electric current to a sealed chamber. As the electricity breaks down the gas an energy is released and resonates between mirrors within the chamber. As it resonates it increases in intensity and at it's optimum is released through a partially transmissive mirror. The beam is then directed to a focusing lens and is further intensified. At this point the laser beam becomes a usable cutting device.

    Some advantages of cutting with lasers include, the ability to cut incredibly complex shapes with no tooling or set-ups. This makes them perfect for production or prototype runs for a huge variety of different products.

    Laser cutting systems cut quickly and very accurately through a wide range of materials. In general, for steel, laser cutting lies between cutting with wire EDM, which is more precise but slower, and plasma, which is less precise but faster. They go well beyond the range of these other methods as well in that they can cut through just about anything within certain thicknesses.

    Given the right material and type of system, tolerances can be held to ±.0005"(.0127mm). Lasers can be found most commonly being used to cut:

    • Most types of steel and aluminum. Large lasers will cut up to 1"(25.4mm) steel and .250"(6.35mm) in aluminum.
    • Paper
    • Wood, plywood, hardwoods
    • Rubber
    • Most Plastics - Acrylic

    When matched to a suitable motion control system, laser cutting provides extremely accurate cuts with a high degree of repeatability over a wide range of materials and shapes.

    Tuesday, November 23, 2010

    DIe Cutting Wood

    Written By Mark Batson Baril

    The question/problem came to Cut Smart basically in this form:

    Designs in Wood, Inc.(alias name for case study) manufactures over 400 different sizes and shapes of small wooden parts in Eastern White pine ranging in thickness from 1/8" (3mm) to 1/4" (6mm) with a surface area under 6 square inches (152mm). Generally the surface areas are 3 to 4 square inches (75 - 100mm).

    Our current process involves bandsawing 8/4 stock and then slicing and sanding each part. This is time consuming and we are looking for a way to lower our manufacturing costs. We have looked at laser cutting but have ruled it out because our secondary process requires a finished, unburned edge.

    I am not completely familiar with steel rule die cutting, and wonder if it is something that we might be able to use. I would be interested in the following:
    • Can this type of wood be cut with a steel rule die (tolerances of .010" to .020" (.25 to .50mm are OK)?
    • What kind of equipment (press tonnage/manufacturer) would be required?
    • The cost of a typical steel rule die?
    • The life of such tooling in terms of number of impressions?
    • The finished edge appearance?

    We answered in this way;

    Because we don't know all the shapes you are cutting it is hard to say what your final results will be. The more flowing and rounded your shapes are the better the results will be. Sharp corners and thin areas of image will be tough to cut. There are several types of dies that could work including steel rule dies, clicker dies, EDM cut specialty punch dies and matched metal tooling. All of these are possibilities depending on the shapes you are cutting and your overall volume. Tolerancing like you mentioned will be tough to hold on any but the machined tools and punches.

    Eastern white pine is a fairly soft wood that can be cut on a steel rule die. The 1/8" (3mm) thickness will be a great deal easier and will give much better edge results than the 1/4" (6mm) material. We have worked with several companies that build models from wood. They use steel rule dies as well as other cutting tools that cut in one hit. They have had excellent results with all of the types of cutting dies mentioned above. Tools other than the steel rule die will work well, but the steel rule die may be the place to start because of its relatively low cost.

    The type of press and the tonnage needed would largely be a factor of how many you plan to cut at the same time on a sheet. One at a time like you describe would require very little tonnage 1 - 5 tons and a very common hydraulic type press would work well. Costs may range from $5,000 used to $20,000 (USD) new depending on the size and style.

    A simple one up steel rule die would cost in the range of $100 to $300 (USD) depending on the shape and who you buy it from. The more images you add to the tool the cheaper each image becomes. Specialty punches and machined tools would cost substantially more.

    Although we have seen manufacturers with millions of impressions on their tools, the material you are cutting is tough. I would estimate no better than 10,000 hits from a tool before it needs a reknife.

    Generally you will find that an extremely hard, thin rule with a very long bevel will work well. Support the rule as high as you can with your base material for best results. There is a rule called "Razor Rule" that works excellent for cutting wood. If diecutting is still something that sounds like it would fit your needs, I suggest connecting up with a local qualified diemaker or diecutter that would be willing to cut a few samples for you. This will show you the type of product you can get and how economical this process may be for you.

    Depending again on the shape of the cut, your edge results will probably have a slight roundness to the top and a square, sharp bottom. Grain, moisture content, sharpness of the tool, cutting surface wear, will all effect the results. Your with grain cut will most likely be of better quality than the cross grain cut. Knots will be a problem!

    High speed CNC routering is another method we have seen used that performs the same way the laser does without the burned edges. Although slow compared to cutting with a die, the method may make sense if laser cutting came close to making sense for you.