Copper Contact

No….. not extraterrestrials.  These are the first contacts from the new progressive die asm that I have been using as an example in my blog posts on Die Design in SolidWorks, Post 1 and Post 2.

The tool build went really well and we were all pretty interested in getting the tool in the press and stamping parts.  We were anticipating that getting the first parts off the tool would go as smoothly as the tool build went.

We have been anxiously waiting for the material to arrive for a few days, so we could do the first hits.  The tool has been ready since Tuesday to go into the press.  The material finally arrived Thursday afternoon, and the press room was able to set up the first die tryout on Friday morning.

We are stamping these parts out a .570″ wide coil of .010″ thick beryllium copper.  As you can see the parts are very small.  You can barely see them in the bottom of the box they are dropping into under the press.

These parts are among the first 15-20 parts that we stamped on our first attempt of getting a strip through the tool.  With the witness marks on the parts from the tool we can see that we are hitting the parts a bit to hard.

Copper Contact Toolkit

Both the 90 degree and the 20 degree form show witness marks from the form punches.  The 90 degree form is showing a good bit of coining from mashing the material to much and the form is getting a bit wide coming around the form.  Our toolmakers will take these parts and also the first strip that they stamped and use those to tune the tool to minimize the witness marks and correct the over coining in the forms.  It is a matter of backing off the shut height of the punches a thousandth or two (.001″-.002″).

After our toolmakers are satisfied that they have some better looking forms they will take the part into inspection to see how the parts conform dimensionally to the detail.  Hopefully we did our job well in engineering and we will be seeing good numbers after inspection on all the cut geometry.

Cheers….

Here in Part Two of my series on die design in SolidWorks I am going to discuss our first design meeting in which we flesh out how we are going to process this part through design and manufacture.

With an official job traveler number in hand it is time to start the tool design.  I will gather up the customer drawing and any other documentation that is relevant to the design and sit down with my Engineering Manager for a discussion.

This particular part will be made out of .010″ thk Beryllium Copper.  It will be heat treated after stamping to a TH04 temper.  Then it will be nickel and gold plated.

The material for the part is thin at .010″, the material thickness will require very close cutting clearances.  For this design we will use a cutting clearance between the die and punch of .0005″.  Also with our punches being small and pretty delicate we will want to use a guided stripper.  The guided stripper will give the punches a lot of support right at the point of their entry into the material.

We will have a stripper to punch clearance of .0002″ (about half of the cutting clearance).  This will ensure that the punches will enter the die and not hit the die cavities.  This would cause shearing of the die.  Shearing is not good in a die as it reduces the die life in the tool from having to re-sharpen the die and punches.  Sheared dies will also produce poor cut edge quality.

Over the years, Auer has developed what we call Master Dies.  These are modular die sets in which we mount the punch holder, stripper, die and punches, etc. into standard chases.  The die shoes; die, stripper and punch holder chases; along with the spring packs, etc., are standard for that master die.  This allows us to offer the customer stamped parts and not have to pay for an entire stand alone progressive or single hit die asm.  We can also turn the design and build around quickly with the standard inserts we use in the tools.  We have over 100 different master die designs in our tool inventory.

For this tool design we are going to use Master Die 103A.  This is a four post die, with a 4 post sub-guide system for the guided stripper.  The master die was designed and built back in 1997. It is a great tool for stamping these small, close tolerance parts.

Master Die 103A

Now that I have all the basic parameters for the tool architecture we plan to use, we will take a look at the customer print to discuss how we plan to handle the part in the strip.  One thing that jumps out on the customer print are the sharp corners on the part (red arrows in the picture below).  This is not a good condition on the part design.

On inside corners it is not feasible to create sharp corners in the punch cavities.  The punch cavities are typically cut with a Wire EDM process.  The wire that we use in most all cases is .010″ in diameter.  This will leave a kerf with an inside radius of about R.0065″ in the corners.  We like to use R.010″ minimum for corner radii.  We can go smaller, but that will require a smaller wire diameter in the WEDM machine, which really drives up costs as the rate per inch of cutting slows down quite a bit with the smaller diameter wire.

Detail Part Drawing

The outside corner, in this case, can be cut sharp, but it will require a cross cut.  It must be cut in alternating passes to achieve the sharp corner.  Luckily for this part our customer anticipated this issue and in the general notes for the drawing we have specifications of R.010″ Max for all inside radii and R.020″ Max for all outside corners.  If this was not specified in the general notes of the customer drawing we would be contacting the customer to ask them to allow the corner radii required to be able to manufacture the part.

Strip Layout Markup

The picture above is what you typically see after a meeting with a couple of engineers who are armed with pencils or pens.  Actually there is a lot of info shown in the scribbles to a trained eye.  We are going to use .0900″ dia pilots and carry the part on both sides of the strip.  The strip will be attached to the flats on the part central to the .059″ dia holes.  We have the grain direction for the part shown in relation to the coil stock.  My job number is 53606, my Toolkit number is 205019 and I pulled part numbers 205020 thru 205074 for my details.

Strip Layout

All the scribbles above are interpreted to look something like this in the solid model.  This is a portion of the final strip to show the general plan for the strip.  In Part Three of my series on die design in SolidWorks I will begin to go into the detail on how we develop the final strip layout for the tool.

Cheers…..

It has been a while since I have posted on how we use SolidWorks at Auer to help us with our designs.  More specifically, what are some of the methodologies and techniques we use to model our progressive die designs.  Matt Lorono’s posts over at the SolidWorks Legion blog on capturing function and design intent got me thinking that it is time to write a series of posts on a few of the techniques we use when designing our tools.

This series of posts will in no means be a complete guide to progressive die design.  The subject is much to broad and the techniques can vary depending on the types of parts you are designing tools for.  But it will cover some of the basic methods we have developed using SolidWorks for the types of designs we create.  There will be some SolidWorks tips, along with some fundamentals on die design and a bit on things to think about to keep your toolmakers and die maintenance folks happy.

One of the main points of Matt’s blog post was designing in SolidWorks for function.  Each design you do has a key part with a key function.  From a tool designer’s perspective, the most important part in our tool design is the strip layout.  The strip layout acts as the road map for the design of the tool and all its stations.

In the strip layout the designer starts with a strip of coiled material that goes through the tool, with each stroke of the press and progression of that coil stock through the tool, until out the other end of the tool a finished stamped part will be produced.  Modeling these steps involves a very different thought process then the process that was used by the engineer to design the part for its function in what ever assembly it will belong.

Detail Part Drawing

The drawing above is a portion of the detail drawing that I received from our customer for the tool design that I just finished a couple weeks ago.  The drawing was pretty complete and very well documented.  We did not receive any math data for this part, just a pdf of their original document.  We will be designing and building the progressive die, along with stamping the part for our customer.

Finished Part Modeled In SolidWorks

Here is the part when complete off the progressive die.  The part is not that complex in terms of cutting and forming.  The challenge in the part is its size (pretty small) and some of the tolerances we need to hold.

Next post I start breaking down the design process used to go from coil stock to finished part and start to develop the strip layout for this part.

Cheers…..