Progressive trends in finish machining

The first thing usually used to take out machine tool marks is to grind them out this can often give a fine enough finish by using the right abrasive. If a super fine finish is required then you can grind to a predetermined under size then electroplate back to a correct size. Hand finishing is best done on cast iron products. De burring etc. Oil stones can be used to polish the surface. Honing is normally used where cylindrical objects require a final finish (lapping). Turned items often require less finishing than milled parts. castings made need all finishing processes to give them the best polished finish.

Thank you for your concern and info.

I've already take an eye on those methods of finishing and so far I've included them in my papers. I'd like to ask you on some inovations in those methods or on some unconventional methods that have taken place recently in finish machining and I should consider them.

Thank you.

Plasma coating, laser vapour, ion deposition, diamond coating, saphire coating, ceramic coating. Try looking up (metal finishing) in google.

Hi,

..that is not exactly what I'm looking for. I mean the finish machining, machining the parts to a very tight tolerances and precious geometry, lower the surface roughness or create a special patterns on surface.

This is an area where I can help. I have been in machining for over 34 years. The latest trends in machining are to machine a part to net finished dimensions without the need for secondary polishing heat treat, or other finishing operations. I have not done hard turning but I have done HSM ( high speed machining ) milling in both hard materials and soft. This is a very involved subject encompasing machine design, high speed spindle technology, tool holding technology, cutter design, and programming techniques. I would be pleased to discuss these at length if you would like. You can contact me via my website at: www.gacampbelleng.com.

Other sources that have great information are: www.creat.com (read the article "machining in the hot zone" . I know the author personally and he is one of the nationally recognized gurus on high speed machining. Another good source is the online magazine "Cutting Tool Engineering".

Rump up the feeds & speeds to achieve a finish like a badgers arse!!!

Did you think this was a comedy forum or do you just like to see a lot of smoke and chunks of flying carbide?

Mssr Campbell is on the right track. I am certain that he will share with you some good ideas.

I would urge you to qualify what is the 'scope' of your definition of finish machining.

Hard turning as mentioned is one approach it is certainly employed in the hard drive industry; Swiss machining produces parts of exquisite precision and finish; We note that most european machine builders are now controlling their machines by cooling spindles (not just coolant on workpiece) thermally to remove temperature effects. Move from gear trains to direct drives/servo motors/hydraulic drives is another source of improvement that will benefit final product attributes.

Thread whirling rather than cutting or rolling threads has been an important innovation in medical implant/ orthopedic bone screw markets.

And of course innovations in materials also could inform your thinking. Success in machining is very much determined by constraints of the materials... being machined. These in turn lead us to consideration of tools and methods.

To be perfectly honest, Using SPC to control processes and development of predictive tool replacement schemes would be my nominees for best technology at 'lowest cost to implement' to improve surface finish. Very few people understand how tools SHOULD fail; and so are unaware of their process being out of control as evidenced by the "other undesired tool failure modes" at work in their process.

Badger's arse not withstanding.

Good luck with your paper.

milo

Thank you Milo,

I also agree with you about SPC. For a small business like mine SPC doesn't have to mean expensive software and tracking systems. Simply by comparing the results of tooling style changes, brand changes, and program changes can provide quite an education. It is absolutely important to look closely at tools to see not just how soon they fail but why. I recently went from a 58 min. cycle time to a 28 min cycle time on a job by changing to a new style of cutter on 2 operations and changing the program accordingly. The tooling cost went to 25% of the previous cost.

I try to learn something every day and I also try to keep up with the latest in machining technology, but you got me on thread whirling. Please explain.

Its running all competing processes out of thorthopedic product space.very high strength threads with very fine finishes using multiple form inserts to create the geometry in difficult to machine materials. did i mention very fast cycle times?

Bone screws are typically machined from difficult to machine materials such as 316L stainless steel or titanium. They are characterized by high length to diameter ratios, deep helix buttress thread forms, and by substantial differences between the root and head diameters. This combination of length, material hardness and depth of cut requires either numerous machining passes or very high cutting forces using traditional methods of threading. These result in longer cycle times and the likelyhood of bowing or deflection.

In operation, the ring holding multiple form inserts rotates at speeds up to 3,000 rpm around a slowly rotating (approximately 10 to 20 rpm) workpiece. With three tools rotating at 3,000 rpm you get equivalent to a single tool operating at 9,000 rpm—eight or nine times faster than typical for single point threading of deep buttress threads. This reduces chip load, minimizing the risk of deflection, while significantly reducing cycle times. High precision parts, such as bone screws and other threaded surgical implants can be produced from rough stock at high speeds in a single pass.

There are other manufacturers but schwanog is the benchmark.

Heres a link with photos:

http://www.floydautomatic.co.uk/pdf/schwanogwhirling.pdf

The europeans (especially the swiss) have been doing this for some time. Ever since the easy work left North America for China, Our shops have been trying to move up the value chain. SO Thread whirling becomes part of our reprtoire.

milo

"the ultimate in personal jewwelry is worn internally"

Your cycle time reduction makes a good point to the original query. "progressive trends"- if commitmemnt to continuous improvement in our processes isn't a progressive trend, well I can't imagine what is. Same with using DOE to optimize process. Its likely his school wants him to focus on the 'technology,' when the real payback is in the 'tech-knowledge-y' and philosophy of continuous improvement.

Drop me a private email, I get to PA a couple times a year, I'd love to visit your shop.

Also, would you be willing to share details of your cycle time improvement for an article or a technical 'white paper?' I can make that happen.

milo

The task of my paper is to classify the finishing methods, describe them and then write about the progressive trends, or I rather tell "what is new" in this field. Hard cutting and high speed machining is maybe rather a subject for my classmates, one of them has to write a paper on progressive trends in turning and one has to write about the same but milling. HC and HSM are no doubt the trends in machining and finish machining and I will definitely mention them and show in some case studies.

By the finish machining I meant operations to achieve more superior surfaces on parts if needed. It could also covers the deburring operations. The progressive trend could be for example: combination of laser structurizing and standard plateau honing to achieve a superior low roughness surface with pocket or cup structures onto it. Those structures ensure the stable layer of lubricant during load and therefore lower the friction. I found some materials about REM finishing, AFM, TEM, ECD and other processes, I'll study them up and propably I'll put them to my paper.

I agree with you, that school wants me to focus on technology, but still it's a bachelor's thesis. 'Tech-knowledge-y' would be expected in diploma thesis.

What the SPC exactly is?

Thank you both for your answers and worth information, hope I'm not annoying you with questions.

best regards

Marian

SPC Statistical Process Control;

www.conicity.com

www.vectron.com

I thought from your earlier answer you were not looking at post processing.

role of chemistry in contibuting to surface finish:

http://www.productionmachining.com/articles/040602.html

Extensive use of through tool coolant in drilling has solved many ills, and high velocity/high pressure delivery systems.

Chip control on tools.

consistency due to insertable tooling as opposed to "journey man's grind."

etc. etc.

If you have a specific taxonomy or questions, go for it.

milo

SPC stands for statistical process control. It is the collecting of data during production for example in machining of: variations from the mean tolerence dimensions, cycle times, scrap, cutter breakage, and any other data pertaining to production. That data is then used to determine what steps are best to improve quality, cut cycle times, and cut costs. Tracking of individual dimensional variances is usually done on a line graph with the center line being the mean dimension.

The reason I noted High Speed Machining is because the process allows for small stepover distances in surface machining. This combined with the other factors required for HSM gives a surface finish fine enough that polishing may not be required. This is the trend particularly in mold making and a lot of aerospace machining and saves a great deal of time and expense.

I hope you do well on your paper.