I didn't see anything here on the topic of stamping or drawing metal over dies. Thought I would bring it up with some questions... I have a couple small parts that I need to make several of and it seems worth machining dies for and giving it a go. They will be made of thin gauge stainless and/or steel. (probably 24 or 22 gage stainless, and/or 22 or 20 gage steel. Maybe even 18 gage steel.). The parts are small, and do not have to be drawn very deep, but I do need them to be reasonably consistent in shape with a minimal amount of surface prep before paint/chrome/polishing. Question is, I'm going to machine the male and female dies and have the design down just fine, but the thing I'm not sure about is hardness. Suggestions on materials that will be reasonable to machine, but will have some longevity? Tool steel? Was thinking I would surface harden the dies with Kasenit. Also, any thoughts on trying to do this with a large arbor press vs. a small hydraulic press? Suggested lubricant or a recipe for one? I would like to hear your input! Thanks!
Small parts, shallow draw, and thin mild steel won't need hardness unless you make tons of pieces. I made a louver die set from some 1/4" x 2" stuff from the scrap place. It was just a little bit harder than mild by testing it with a file. I punched some louvers with it in a big vise, and did not need to pre-slit the metal where the louver would be sheared. On mine, the male die is way more important than the female. My female for the louver was just made from 1/4 steel strips standing up as an outline of the louver shape. It had a flat bottom because the male did not need anything else to push against besides an outline. the knife edge of the male die got dull at the end of the job after 12 louvers, then it was tearing a ragged cut.
Depending on the complexity of the shape you're trying to stamp, you might be successful with a simple male die and a soft backing pad and run it under a press. Basically embossing. <object width="480" height="390"><param name="movie" value="http://www.youtube.com/v/eA0ky3Z5nk0?fs=1&hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/eA0ky3Z5nk0?fs=1&hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="390"></embed></object>
Scooter, how many of whatever are you needing/planning to make. Mild steel dies should last for 10-20 strikes depending on the complexity & depth of draw for steel sheet. for stainless sheet they would last for less strikes. The lube used for most low production stamping is usually an animal based lube like lard (yes lard!). for mass production we use a synthetic lube but it is pricey. (And slipperier than bear snot!) If you are planning to make lots of copies of whatever you are building then hard facing the striking surfaces is a good idea. The parts will be more consistent from first to last and the dies will survive much better. This is the stuff we use on our dies at work: http://www.tdcoating.com/applications.htm We usually only do this on the upper die & then only with deep draw parts. The rest of the draw die striking parts are made from tool steel. The dies we use at work have to be reliable for one million strikes plus. Depending on how many copies you are making, tool steel might be OK. Here are a few short vids for your enjoyment. http://www.youtube.com/watch?v=SLmQ9pkEz7Y http://www.youtube.com/watch?v=yEjo6WHhIEk http://www.youtube.com/watch?v=i_LODwlOIEY These are some of the machines that I have run daily for about ten years now. The big press in the videos is a 2500 ton press, we also have in our shop a 1500 ton & a 3000 ton. the other two video's are an 800 ton progressive feed press and a 600 ton blanking press (to make the steel blanks to feed the bigger presses) If you have any specific questions PM me & I will try to get an answer for you.
As was said for short run non complex form a low carbon less may work . As a tool and die maker we usually used d-2 die steel that is provides in soft form and shaped everything to within .010 oversized . The d-2 is then heat treated and the finish size is ground into the die shape . This will require planning and much time . This will guarantee the final shape and a consistent piece each and every time for many thousands of parts. It's the initail cost that kills you. The brake even point is sometimes a couple of hundred or more parts to recover the need for an expensive die set. Hope this helps
4140 will work for quite awhile even without hardening the dies my experiences making muffler parts it may take some tweaking of the dies to get where you want to go and metal is veryimportant as to drawability AK DQ for sheet steel amy have good flow and formability, look around and try stuff untill you get it to work
anything that has a deep draw requires some kind of die cushion, you need this to avoid wrinkles, if its just a emboss of say 1/16" with a 1/8" offset between the punch and die, and your doing 20 ga, your tooling can be hot rolled and i bet you can get 10,000 parts out of it. my company logo made from 20ga brushed stainless, tooling made from 16ga hot rolled. heres a die cushion http://www.youtube.com/watch?v=pRa0TOKsw68
Material thickness and quantity are your biggest factors. If you are using stainless steel.. I would recommend A2 or D2, tool steel. A hydraulic press /arbor press are fine up to a certain tonnage. If I can be of any help. pm me.
Interesting stuff and some good discussion here! The number of strikes/draws will be low. I don't foresee doing more than 20, but I will use up whatever materials I have left, so it could be as many as 100 pieces/strikes. At LEAST 10 of these will be stainless steel. Possibly all of them. So I would like to plan for the worst case. This is only cost effective and worth the effort if I can accomplish this with what I have in the shop. I do not want to sub-contract anything out. I guess you could say it's in a sense, an experiment, of sorts. I have the ability to machine the dies here and if I have to build a simple press of some kind using a bottle jack, or something, then I will. Trying to keep this simple. The part will have a max draw of about 1/2". One part is sort of a "T" shape with 1/2", or so, wide leg and top bar and radiused inside corners and faces. Bars are short in length. The other piece is sort of an oval shape, again with about 1/2" draw and 1/2" full radiused thickness. Hope the example shapes make some sense. I was hoping to hit my local steel supplier and find some steel rems that could be machined to work. Maybe some 3/4" plate rems, or something. I only have two shapes to make (two male and two female dies) and if I have to spend $400 on some crazy die materials for low production numbers, then none of this is cost effective. Would I need something to keep the two dies from mis-aligning during the draw, like alignment pins or maybe fitting the male and female dies into a fixed tube to keep them aligned during the process? Explain more about the "cushion" that was mentioned!
When you machine the dies, reference 4 dowel holes at the corners of each die plate. Then you can pin them together. Doesn't seem like you're trying to do this as a high speed production process, so load time isn't an issue. Any press with the nuts should get it done.
Some 4140 or p-20 should get you to around 28-30 rc which would be plenty good for short run.I could be nitrided latter up to much harder for more life if needed.Most of the stampin dies we do are cpm 10v which is powered metal and can take alot of abuse but it gets realy tough.We just machined some the other day that was close to 68 rc.
A cushion has to be used when drawing steel otherwise it will wrinkle badly. Sounds like you are not drawing it,,only 1/2 inch deep,,that is more like embossing. You won't need a cushion. I cant see you making any kind of tooling for under 400 bucks,,,,they can be made cheap,,but not that cheap. What are you trying to do? Tommy
I did some quick drawings of a simple "theoretical" set of dies. The "T" shape, I mentioned seemed simple to describe, so I drew that. My part doesn't really look like this, but it embodies all the same issues that the part I'm thinking about will have. Let me know what you guys think... I was thinking a little bit of "planishing" might be good, but maybe simply cutting a full "T"-shape thru the material for the female die would do plenty good with no planishing required. Here's the female idea. (blue shows the working faces) The male mounted to a base plate with the 4 alignment shafts. (blue shows the working faces) Side view of the die set unloaded in it's final position, or close to... How it would load... (might need something to keep the blank sheet metal from sliding around) Loaded side view... (22 gage stainless blank shown) The result with these dies would be the unknown, but I'm thinking the inside radius would be the potential trouble spots, the ends of the "T" would sort of be free to move about, but a lot of it would be trimmed off anyway. No big deal. So... Thoughts? Suggestions? What type of tolerances should I have between male and female dies, and the material thickness? The parts I'll be making aren't anything precision and aren't anything that will be produced at a fast pace, by any means.
You have some DQ steel? I have some AKDQ here that they use to make hood scoops out of. Stamps real nice.
The concept will work, but you need a pad on the bottom to control the material. For short runs I've used rubber under a steel plate. That plate will also be used to locate the blank. I have draw lubes you can use. That shape shouldn't need DQ. If you use stainless, start with at least 22 ga. 20 would be better. 304 or 304L annealed would work fine. It depends on why you want the stainless. .
Didn't forget about ya'! Figured we'd chat more at breakfast. And actually, I was hoping you would see this and share the knowledge! The plan worked! I'm having a hard time visualizing where the pad/rubber goes. Are you saying it would go between the blank to be drawn and the male die?? Confused...
I never tried to stamp a part like that with the flat sheet of steel cut to the T shape beforehand. I wonder how it can stay in the perfect stable position inside the dies, as the pressing starts?
Scooter, you have a way of getting my interest piqued. Now I am going to be wondering what the hell you are doing now. Probably won't get any sleep tonight.
I'll take some pics tomorrow. Here are the louvers. Someone torched out the two cowl vents and rather than fill the holes with flat steel, I louvered the patches first. All done in a big bench vise. Huge pics on full expand, you can see a good sharp detail crease around each louver.
Good tips here! Was wondering about using a tail/tab or three, to control the part's location. Then trimming.
I guess the blank could be larger to allow for mis-alignment when loading the blank. Just has to clear the alignment pins shafts.
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