tooling wear and aluminum build up

[kenjr]

i could use some suggestions in selecting a coating or material change to prevent tooling wear and aluminum build up in our tooling.

without disclosing to much information our basic automated manufacturing process in place is as follows;
an aluminum cup is placed into a nest, a funnel is then put on the nest and over top of the aluminum cup, a small amount of powder is dispensed into the cup through the funnel, the powder is then consolidated via a punch passing through the funnel, the funnel is removed, the part gets a closure disc put on it, the cup is then crimped closed and is then removed from the machine.

3 problems:
1) our largest problem is aluminum build up in the nest and crimping dies. we currently do a lot of soaking our tooling in sodium hydroxide and polishing to remove the build up. 2)the heart burn with all this polishing is the cost of production down time and the operator doing polishing instead of making parts. the other porblem is tooling wear that is introduced from all this polishing. 3)another problem is that the funnels tend to get a powder build up on the funnel edges so we get uneven powder dumps.

the tooling:
the area where the part is nested is small...approximately 0.095 in diameter by .500 long. the tolerance of the tooling is plus or minus .0002 in most cases. the tooling is made of O-1 tool steel and has a hardeness of RC 60-62. the surface finish that is called out on the drawing is a #8 finish but i question how close our toolling really is being recieved in at. currently there is no coating or plating on the working surfaces of the tooling.

we are open to any suggested changes in tooling material and or a coating/plating that we could apply to the tooling to imporve the quality and longevity of our tooling.

thank you to the group for your help.

[Gordon]

Hi kenjr

to the Surface Engineering Forum.

Consider CVD (Chemical Vapour Deposition), TC (Thermoreactive Diffusion TD) and possibly other diffusion based treatments. Only problem here is that they are high temperature processes. Cooler processes tend to be line of sight restricted such as PVD (Physical Vapour Deposition), Thermal spray etc.. which I think will not be suitable due to geometry of your parts.

A few links to get you started (note - not a recommendation, just first sites I came across )

ToolandDie_Article
http://www.richterprecision.com/

[kenjr]

i'm not sure if a Ticn coating is exactly what you are refering to but we have tried that on crimping dies and we still seen build up of aluminum. i thought maybe the reason for the build up was because this coating needs speed to work well i.e. endmills. the use of lubricants is not an option because we have to seal the parts when done and the lubricants wont allow the seal to stick to the surfaces that is neccessary to create the seal.

thanks for the info and the sites to check out. it is much a ppreciated. i will follow up with some research and if anything good comes out of it i will post the results.

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after reading the first article you sent i can see why our crimping die that was Ticn coated failed and got aluminum build up in it. the initial surface preperation prior to Ticn application is a very crucial step in order for the coating to do its job properly. i would have to guess that our finish in the die was less than perfect and that was the reason for the failure.

[drramc]

You can try Spark deposition of carbides,using parameters to get smooth surface finish. For details, chack with my book 'Advanced Thermally Assisted Surface Engineering Processes',Kluwer Academic Publishings,(now Springer).Price $167. There is a chapter on Spark deposition process,inclding basics,equipment, processing parameters,deposit chacteristics,applications (mostly on tools )
ram chattopadhyay