Customer Login - Register

Where engineers, die designers
& suppliers meet.

Die Shop Manager Create Entry
It's the Material!  No.  It's the Tool!  No.  It's the Material!
It's the Material! No. It's the Tool! No. It's the Material! By: Jim Szumera - MACOR Published on: 05/14/2012
It’s the Tool! No. It’s the Material! No. It’ the Tool!
Again, sound familiar? In the previous segment we talked about the tool versus the press. All too often the tool seems to be blamed for its inability to produce a quality part. This time we will examine the raw material and how it can affect part quality. We will also look at some corrective actions involving both the tool and material.

The properties and specifications of the raw material are the inputs that control product quality. Most raw materials are purchased in the commercial grade, which happens to be the lowest cost. Basically, profit margins and competitiveness drive that decision. Understanding that, we can now look at the affects of the properties of the raw material. Most commercial grades are specified with a temper or hardness variation of 15 points on the Rb scale. In percentage terms, that equals 15% using a scale of 100 points. That represents a huge swing. This temper variation affects the formability of the part. This attribute makes it very difficult to control precision bends consistently. Allowances and adjustability should be designed into the tool to accommodate the variations in the material. Adjustability is also important in compensating for material thickness variations. Another important property of raw material is the elongation factor. The elongation is the materials’ ability to stretch. The elongation is usually expressed as a percentage relative to a given area. The ability to stretch form increases with a higher percentage number. This is critical in draw forming, extruding and possibly forming. Stretching or thinning material more than its elongation usually results in part failures. Most materials also work-harden somewhat during the stamping operation. This is especially true in draw forming and extruding. If all the correct tool design factors are utilized and the part is still cracking or splitting, the part may be work hardening during the stamping operation. If that is the case, I may consider starting out with a material with less temper and let it work harden to specification. This would require an “in process” print as well as the final drawing specification. Another method to eliminate splitting is to temper the parts between draws, or zone tempering. Of course, this does increase the costs. I did say all the correct tool design factors, such as draw radius, air release holes, proper reductions, proper blank holder pressure, but we must also consider improvements on the tool build side. These improvements are draw polishing, such as abrasive flow machining, upgrading the die steels, and possibly the lubricants as well.

Keep in mind that the raw material specifications still used today are nearly 100 years old. Raw material can often be specified to meet your different applications without added cost. I have worked with clients who have actually specified “must make a good part” on their certification demands. Most reputable suppliers will meet or exceed your in house specifications. The material must be controlled, specified and inspected accordingly. The tooling, depending upon the volumes and dimensional criteria, should be designed with adjustability and accommodation. There is no magic wand solution, or one size fits all. So, in conclusion it’s the press, it’s the tool and it’s the material. Next time we will take a closer look at running old machines to make close tolerance parts.
Post a Comment


DaveMay 15, 2012 - 9:12 pm
As a manufacturer of CNC wire, tube and strip forming machinery, poor material cannot be overcome by controlled processes, however, good material with controlled processes produce good parts! The two are dependent on each other, however are often purchased independently. Therein lies the flaw.
JanMay 15, 2012 - 9:14 pm
SSS...It's the tool in the hands of a skilled craftsman which gives the finess of the product irrespective of the material.
KevinMay 15, 2012 - 9:16 pm
It's the material! Good material is a must at tryout!
PeterMay 18, 2012 - 8:09 am
I worked with a die maker that was notorious for coming up with all kinds of ideas for the design of the tool AFTER it was built and tried out. But in our brainstorming meetings before-hand, he was silent.
Ed KMay 18, 2012 - 9:04 am
I think Peter only left one thing out...the Die Makers blaming the Die Designers. At least during the construction phase if not long after
Scott RMay 18, 2012 - 9:06 am
I guess I am lucky in that reguard. I have to design, and build my own.
Deryl MinnichJun 26, 2012 - 9:41 am
Whenever I used to encounter a material issue such as a split, I would first check the material cert. from the mill. Then I would do some quick trouble-shooting of the tool. Before diving deeper, or checking the press, I would cut a blank from a different coil of a different lot # and run it through the tool. This usually told me right away if it was the material
ChuckJul 1, 2012 - 3:49 pm
We blank/draw and then form printed 0.010" tinplate steel. More often than not, our problems are related to print being part of the lubrication process within the blank and draw operation. Variables created during the printing process coupled with temper issues are the usual culprit. We most often challenge that theory by running a different print number, but in the end, once it's cut to size for our presses, we own it and have to more often than not "make" it work, even when such tooling changes challenge future runs of better quality materials. Tooling maintenance (costly) is the inevitable result to reclaim the ability to run quality material combinations after modifications have been made to accomodate lesser quality material combinations.
TwotenthsFeb 25, 2013 - 12:36 pm
Most material is basic and easily workable but on some occasions the required material strength and the required end result in shape takes the material to the edge. I remember a particular case where our best outsource tooling company could not get the tool to make the part without splitting from various directions. It was a Suzuki motor mount bracket. All previous brackets similar for the big 3 are made of much thicker material that is much more malleable. Usually it's made from the standard hot roll material with a galvaneal coating. Suzuki on the other hand wanted to use thinner metal but stronger. Well we all know that stronger means less formable. PPAP time came around and there were no parts and no solutions. The tool was shipped to us as is because they could not make it work. I was approached on a Wednesday about it and they told me to have a look and see what I could come up with. They told me to take my time there was no rush. I spent the afternoon looking at the tool and a basket full of split parts. Every part had splits in a different place. there was a lot of necking where the part is on the verge of splitting but gave way in a different area. Thursday morning came around and I was approached by management and told that they needed parts by Monday. So much for take your time. It was a real puzzler. If a part splits in the same place then you can address it but when it is inconsistent that means that you have no control over the process and it is not even repeatable. I spent the day trying to find a solution. Meanwhile my supervisor came and told me that I would have to work the whole weekend on it including Sunday. I have never worked a Sunday in my life. It is a religious holiday and a family day as well. He was adamant about it. I must work Sunday. I told him no way. He threatened me by entailing that if I do not comply I may not work there come Monday. I told him that I would put in all the hours I could and find a solution without working on Sunday. He didn't believe me and voiced his opinion right away. I said that no matter what it took in hours I still would not work Sunday. I would solve it before then. He said If you do then I will pay you for Sunday as well. By that time I had a new approach in mind. It is too complicated to explain in words but I had noticed something that may be causing some of the problem. The part shape coming from the previous station was being forced to move in three directions at once in this station. The solution came to me to create a template from paper that gave me the shape of the part from the angle of the draw in the station where the problem was. It was doubly complicated because it was being formed beyond 90 degrees to an actual 110 degrees while maintaining a U shape and forcing the side flanges open all at the same time. The mating block on the bottom section that both wipe and draw the flanges was a 90 degree surface with shape. When the part was forced down to draw and wipe they collided with the part at a 20 degree angle and the block was designed at 0 degrees or flat with the contour shape roughly put on it. You could tell that the block had been modified many times. That put the force way out on the flange before establishing a bendline to draw over. My paper cutout I set at a 20 degree angle and made it match the contour at that angle. I now had the shape at contact time to establish the bendline. I took the paper and glued it to a block of P20 prehardened. I offset the block on a 20 degree angle and started running passes with a flycutter. I followed the contour exactly each time just touching the paper edge. I would step up or down in .050" lateral increments and come down until I just grazed the paper and do it again over and over until the entire shape was complete on the block of steel at a 20 degree dropoff angle. I had figured that I could take a disk grinder and keep grinding the high spots until it almost blended. I roughed it down very quickly. When I was very close I changed to a rough flat stone and worked it like a file. Curving the stone to the shape with every stroke until fully blended. I gave the edge that I had to draw over a small 1/8 Radius to start. It's easier to take it off than put it back. I put the station back together and put it in the press. I slowly started to work the radius starting where the largest splitting was. Making the radius bigger to relieve the high tension high stress areas to lessen the splitting. There was no simple solution to stop the splitting because stress cracks were on all sides and splits were in three main areas. I saw no signs of splits or fatigue in the corners of the flange so I left the corner radius small and opened up the split area radius until the splitting stopped in a certain area. That was the start and I just I had to play with each area separately. When I worked on the next area the splitting might again return to the area I had just completed. The force had to stretch the material from the corners to the inside and outside areas of the three faces in-between the corners. It was quite difficult to balance the forces evenly but I could tell that we were of the edge of what the material could handle. A small scratch or imperfection would cause splitting. I managed to get it running by 9:00 AM Saturday. It ran fine and you could see very minute necking on all three edges but no splits. As the time went by and we received new coils of material splitting started again and no matter what I did I could not totally control it. I managed to get a 10% scrap level but no better. The material was along the knife's edge of what was possible. In this situation material was the culprit but not out of spec. The spec's allowed for even harder material. Those coils could not be run in any way possible without large scrap numbers. The process was already running at the breaking point and the specs could not certify usability. To tighten the specs made the material too expensive and would erase the profit margin. Worst case scenario was a batch of material with a 35% scrap rate due to splitting. Lubrication had no impact on scrap levels no matter what we tried. There was a dry on micro silicon bead formula lube that actually did make an impact on split levels but a 5 gallon pail costs $1000.00 and you can't thin it out with water or any other liquid because it affected dry time and lost some of it's potency. There are limits in how much you can pull and stretch materials. The harder the material the less you can form it.
Return to Top
It's the tool! No.  It's the press! No.  It's the tool!
It's the tool! No. It's the press! No. It's the tool! By: Jim Szumera - MACOR Published on: 05/14/2012
It’s the tool, it’s the press, it’s the tool!
Sound familiar? In my 40 years experience this has been the argument in every metal stamping operation when it comes to dealing with persistent problems. The tool department points to the punch press as being the culprit for quality issues, tools shearing or chipping. The production department, usually with top management concurrence, blames the tool and the tooling department for any causes, delays or quality issues. Management, especially, points to the tool because it is there. It can be worked on, shimmed, modified or sharpened. That’s easy. The tooling department usually gets put in defensive mode. The last thing management wants to here is that it is the press. Fear sets in. Buy a new press? No way. First, let’s look at the entire marriage. Is the die a proper fit for the press? The fit involves the force, area of bed and ram, condition of bolster, balanced tooling, speed, lubricant, and sensor protection. The aggregate force required should not exceed 75% of the rated force of the machine. The force calculation should be made at the point of material contact. In other words, if I am stamping a ¼ inch thick part I must calculate the press tonnage ¼ inch off dead bottom, which, in many mechanical presses the force applied drops off significantly.
Is the bolster and lower shoe supported throughout and not flexing? Is the die a good fit between the uprights left to right and front to back? A general guideline is 75% bed area. Does the tool have a balance or spread out the forces? If not, damage to the press bed and ram will eventually occur. Are we too aggressive in running above rate? Is the rate possibly too high for the application? What can be done to improve the rate? The last variables are lubricant and sensors. Is the die lubed properly and thoroughly where needed the most? Are sensors in place to prevent die damage? Finally is the press of reasonable accuracy and parallelism. I look to have at least .001 per linear foot of flatness of the bolster and ram. The ram and bolster should be parallel within the same.

Now let us look at the tool. Has the tool satisfied run requirements and been tested properly? Given the tolerance of the part, is the tool process capable? Is the design robust? What are the weak points, if any? Has the tool been check listed thoroughly? Finally, is the tool mathematically correct? Is it timed properly? The answer is to methodically eliminate the variables and improve the process. Watch for next month’s article on “Running Old Machines”. We will cover many tips and ideas to improve the performance of older machines and improve part quality and tool life at the same time.
Post a Comment


StephenMay 15, 2012 - 9:19 pm
It's both...Don't expect good results if you put a well made tool in a poor press, or if you put a poor tool in a good press. The press needs to become part of the tool, and visa versa.
ChuckMay 15, 2012 - 9:23 pm
That's why we do things with cross-funtional teams. 8D corrective actions or 5 Why analysis are great tools for getting to the root cause of the problem. If you can't resolve it assemble the TEAM.
JonathanMay 15, 2012 - 9:25 pm
It's the operator! No. It's the die set up! No. Its the double blank! No. It's the broken punch! No. It's the tool and die makers thermos!
PeterMay 16, 2012 - 7:41 am
It's the press operator! No, it's the diemaker! No, It's the press operator!
Too much finger pointing and not enough problem solving.
ChrisMay 16, 2012 - 7:43 am
Don't forget the gage sucks
ScottMay 16, 2012 - 7:45 am
Wow Peter, Lol. I can tell you have been aroun the block.
FredMay 18, 2012 - 8:10 am
If your stamping parts for "much" of the medical industry or for military use you must qualify the tooling along with each press it might run in. For small precision parts that is easier said than done. Two band new identical presses will almost certainly produce a different part. Close maybe but identical not too likely. May not be noticed in an 800 ton blanking operation but cutting and forming .002 thick Platinum, Stainless, BeCu, etc. you will see measurable changes between presses. For that matter take a die out and put it back in without even opening it up and there will be part changes. Must place die EXACTLY in same location and torque all clamps to exactly the same repeatable values. Then there is dirt, oil, etc that can ruin your chances for a repeat performance as well. Many debug hours are wasted making up for poor press setup procedures. I should write a book except those that need to read it wouldn't. AND don't forget the feeder the straightener the dereeler. Each can and will cause part changes in the press. OH by the way does your raw stock EVER touch the floor? Better not or there you go again adding another variable. and NEVER change press speed without checking the parts. Another for sure variable.
DerylJul 5, 2012 - 9:21 am
There are many variables. Good trouble-shooters are hard to come by. Most trouble-shooters I have worked with over the years usually gave into finger-pointing quickly without getting to the true root of the problem. This is why good trouble shooters are hard to come by. This is also why good trouble shooters have a hard time advancing in a company, because they are so valuable in their current positions. I will never forget what the owner of the company I apprenticed at said to me when I first asked to work in his tool room...he said get good at trouble shooting and you will go far. Anyone can put together a puzzle, it takes real talent to solve a problem.
TwotenthsFeb 25, 2013 - 4:09 am
I am a very good trouble shooter. There are some simple cost effective things that you can do in the design stage of a tool that will alleviate some of the press problems that cause die problems/damage. Presses age and also press abuse can trigger some of those common problems. Misfeeds from old feeders cause a lot of damage to tools and presses as well. We have all new dies fitted with feed protection sensors now. We implemented a design standard that really helped with older presses. All our tools use standard corner pins but we also have added corner posts as well. These are solid corner blocks welded to the dieset and fitted with solid square plates in two directions on each corner. The lower plates are solid hardened tool steel plates. The upper plates are graphite studded bronze wear plates. They help to support alignment in the last 4"-6" of the stroke when the working parts of the tool come together and begin loading with forming and cutting pressure which is not always a balanced load. In an older press the standard guide pins are not strong enough to overcome the ram shifting on older presses. The corner bidirectional plates along with the guide pins can overcome most of the lateral shift in older presses in an unbalanced load. Over time the corner die plates on the upper shoe will wear because they are bronze and made to wear. The thickness of these plates are standard and repeatable when purchasing replacements and when you are in a position where you don't have any spares you can resurface them and shim them back out to the standard thickness. This has indeed help a lot with the older presses that should have the slides replaced but due to lack of maintenance time and down time restraints are never corrected.
TwotenthsFeb 25, 2013 - 5:22 am
@ Deryl,
There is a price to pay for being a good trouble shooter. Most tools can be serviced and /or repaired by most good toolmakers. The problem with being a good trouble shooter is that by the time they realize that it is not a common or quick repair the time has run out and the die must run again. It is usually at that point when I am the person to see. First problem is "when do you need it?" I needed it yesterday. It is the truth because it was supposed to run at that time but when they tried, it couldn't make a good part. The pressure is on. The management starts watching like a hawk to make sure that it is being worked on. First you need to know what the others have done. It might have exacerbated the problem so it might need to be undone first to get it back to the original state of inoperability. Look at the strip to determine where the problem may have occurred. Look at the tool to see if there is anything obvious. Knowing what was already tried helps because you don't need to repeat it. I am and always was the person of last resort because I tend to be involved in many such problems and am probably finishing off the last disaster. The problem was very complex and you needed to think outside the box to find the answer. It was a 2 off tool left and right hand parts. both parts had become elongated stretching from the centre carrier which is a solid 1" wide 3mm thick strip of material. The parts are box shaped and pull material from the outside into the form block with a draw pad for pressure. The bottom sections had been polished to mirror finish but was still elongating and pulling from the carrier side. Pressure pad had been polished as well. My boss approached me and asked me my opinion of what could be wrong. I had been looking at the punch that was drawing the material in creating the v shape before later being folded up into a box. I told him that from what i could see that it might be the punch causing the problem. He strongly disagreed and said you can't make steel go uphill against the pull. I took a very close look at the punch and it looked fine. It was fully hardened and all the radius surfaces were well polished. The crown or top surface of the punch was v shaped with the center being the highest point. I rubbed it with my fingers and it felt pretty good. I decided to take my fingernail and drag it across the crown surface in a motion against the movement of metal across the crown not with the movement with the movement you can feel no inconsistencies and it looks as good as it feels. When I dragged my nail across it it the other direction I could feel slight scratches imperceptible with finger touch but perceptible with nail dragging. I told him to get me the diamond paste so that I could do a mirror finish across the grain. He though I was crazy and kept telling me that you can't make material flow uphill. I beg to differ. All the material had to come from the outside of the strip and pull into the middle. There was no give coming from the middle because it was solid at that stage. I told him that the material had to flow over the crown to flow into the die opening. The scratches were in line with the material motion but only perceptible when running across the surface in the opposite direction to the flow. It meant that the small scratches even though they ran with the movement were enough to slow the stretching and make the side too long. He was pissed at me and stomped away. I took the crown of the punch up to a mirror finish moving across the grain to even it out and flatten the small scratches. I then polished it in line to the movement to finish it off. I put it back together and sent it out to run. My boss came back and told me that I couldn't leave until it was making good parts. I had remembered when the tool was new that the length was perfect and over a year was slowly getting longer. It takes some time to get it in to the press and set up again. They were running another tool while waiting and it had to be taken out first, I waited around a half hour or so. It took a little longer to put the coil back on and restart it through the tool. My boss was standing beside me not looking too happy. After it was completely through the tool he turned on the automation. It started stamping away and I let it run 20 or so pairs before checking them. I took the last two off the conveyor and put them on the check fixture. Not only was the tab shorter but it was back to what it made in the beginning when it was new. A perfect length. I looked at my boss and went to put my tools away. I got ready to go home. My boss was totally astonished and speechless. I left. Proved him wrong again.
Return to Top
Marketing in Texas and Nationwide
Marketing in Texas and Nationwide By: Johnny Martin - Encore Multimedia Published on: 04/25/2012
Encore Multimedia is a full-service advertising and marketing agency in the ArkLaTex that is expert in all facets of Internet marketing, Web design, graphic design, Web development, print advertising, video production, public relations, and media buying and placement. Not only do we offer a number of individual marketing services, but we can also build and implement an integrated branding/marketing/advertising campaign that fits your budget and surpasses your goals. We penetrate markets in Houston, Dallas, Fort Worth, Austin, San Antonio, Shreveport and other markets nationwide. Our expertise in online social network advertising, website design and promotion is backed up with know-how in targeted audience marketing research, strategic marketing, television advertising, and high-impact print campaigns for highly successful branding.
Post a Comment

Return to Top
  Page   1   2   3   4   5   6   7   8   9