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high speed machining

odessa

By odessa,
in Industrial Forum

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Posted
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Does HSM-advisor compute the force that will try to pull the endmill out of the collet? We currently use only ER-collets and I constantly fear that the collet will give out long before the endmill does. (One of those neat HydroGrip holders would be great...)

Nobody calculates that, lol

 

Really shouldn't be using ER collets for milling at all, especially heavy duty HS Milling

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SlaveCam Collaborator

SlaveCam

Posted
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Nobody calculates that, lol

 

Really shouldn't be using ER collets for milling at all, especially heavy duty HS Milling

 

I know :) All our heavy duty milling is done by high feed milling cutters. But there are occasions where dynamic toolpaths would work better. There's only a handful of weldon holders around and if none available, no change but to put it in an ER collet.

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zero_divide Newbie

zero_divide

Posted
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Nobody calculates that, lol

 

Really shouldn't be using ER collets for milling at all, especially heavy duty HS Milling

But my calc does calculate that!

 

In results area it shows the Torque on tool.

If one had information with max holding power for their holder, he could use it to determine if pullout / slippage could be an issue.

 

Generally I notice that setting Torque Limit to 100% in HSMAdvisor completely eliminates slipping for properly tightened ER 32 holders.

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jlw™ Newbie

jlw™

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We run them like crazy. ER and TG collets. The only time we have trouble is when the cavemen over tighten and crack the nut or run a damaged collet.

 

I personally do not like rigid side lock holders.

 

Granted, if I had my way we'd have rego fix powrgrip or heat shrink but not every shop can or will spend the money for it.

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crazy^millman Veteran

crazy^millman

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Well I typed this yesterday in between some toolpaths crunching and sure some will take it positively and others will take it negativity. However here are my thoughts on this subject. Not meant personally or against any one person so hopefully that is understood.

 

Running HST toolpath in ER-Collets a company throws out $1000 or more gamble every time they run a part. Why take such a gamble?  A good holder can be used on 1000's to 10000's of parts. You do the math and someone is tripping over $100 bills to save pennies. Holders are the cheapest part of any equation when it comes to machining parts. Why do companies still to this day cheap out on good quality tool holding? I say it is because of a lack of understanding of today’s toolpaths and machining processes. HST toolpaths are game changing methods and processes for today's companies looking to maximize profits and efficiency. We have seen on some projects using HST toolpaths 50% savings over traditional processing and methods that were accepted as the best that could be done. One customer on their machines felt the best tangency factor that could be run was a factor of 7. Machine accepts 0 for loosest tolerance to 10 for the tightest tolerance. In previous attempts to High Speed Machine parts using a different CAM Software they came to this conclusion. With Mastercam 2017 and the HST we went to a 2 tangency Factor and on the 1st part the roughing time would have been 46 hours running the machine at the previous accepted best practices. We got it down to 23 hours. What does this have to do with tool holders one might ask. Everything the customer is using Shrink Fit and Balancing every tool that runs on their machines. Had this been attempted with a ER-Collet we would have never got the same results. This customer has over a $200 shop rate. By investing in the right technology with regards to tool holding they allowed the process to be maximized. 4 of these parts every time it needs to be run and plan to run these parts 6 times a year. One this one part because of many factors they have seen an almost 100-hour reduction in cycles times. In one year that is a 1200 hours swing because of using the correct holders being part of the equation. This number is for the people who keep saying good quality tool holders are expensive. This company on the 4 parts per set is seeing a savings of $240,000 yearly. How many holders can that buy? How important is competing with today's demanding want everything now mind set not using the right solution working out?

 

Running parts with HST toolpaths in a ER-Collet is not smart from a business side of things. The risks and possible issues far outweigh the cost. Wonder why machine are not being run efficiently starts with the top. The company that is cheapening out on the must haves like good tool holding can expect the same all the way through a company. People, Process and Technology are 3 parts of the manufacturing triangle. Tool Holding supports the Technology to improve the Process to allow the People to be good at their work. Break that leg of the triangle and you might get lucky and not have an issue, but why send that kind of signal to your employees and eventually your customers?

 

I talked about the signal not having the right working holding sends. People who have not machined parts see a $50 holder and a $350 holder. They only looking at the price tell the person trying to purchase the more expensive tool that is a bad decision. Again because of the lack of what I explained above they make this common error. They are risking things seeing the immediate cost and not the long term costs. That employee has done their research and chosen that tool because they know it is the right tool. When management shoots them down they defeat the person looking out for the company and are devaluing their efforts. Human nature is to do the best job you can do. For a CNC Programmer making a NC program that makes good parts is rewarding. Being able to push the technology of the CAM Software and the Machine Tool becomes more of a thought when someone feels management wants and embrace that. When Management makes that cheaper decision to not support choices in that direction. What signal does that send to the CNC Programmer? One part of the conversation is faster, better and more efficient, but then the actions to back it up are we are cheap and expect you to make miracle happen. Technology is changing and to use it to its fullest a company most provide its employees with the correct process purchasing the best solutions. It is a balancing act with a business spending money in the right places, but tool holding is one of those areas that spending is money well spent.

 

Sorry for the long winded response and came back to this many times before posting it between toolpath crunches, but hopefully the spirit of what I am trying to communicate comes across in a positive thought provoking way. Not a negative me trying to be mean way.

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mikenaturalice Newbie

mikenaturalice

Posted
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@Ron. You seem to have atypical experiences, at least to me. I would not argue any of what you said, but I think very single place I have worked for has the mindset of "buy the best value", which to them is never the really the best, its a copout way for them to buy just one step up from the cheapest junk available.

 

Keep in mind as I say this today I am working at a multibillion $ company, that still won't spend money on machining related stuff. So I don't think what I said previously really has much to do with a budget, it seems to be a mindset. Although it is fair to say that machining is not our primary, or even secondary, business. It is still frustrating however...

 

One time we needed to buy a precision boring head for our first cnc milll (years ago, different job) and I argued for a high end tenth setting type. The owner pooped himself when he saw the price so he went with a cheapo bare bones Criterion (yes, I know). Surprise surprise we struggled to get holes in tolerance.  :ouch:   I know we paid for that precision head over and over again in time lost fiddling around, but the owner just couldn't see it. 

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jeff Newbie

jeff

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The only tool I've had pull out this year was in a solid holder; the ER's have held firm.

Was it a hand-ground flat? I hand grind flats on almost all of my tools with just a pedestal grinder and green wheel.

The only time I've had a tool pull out is when it's not ground correctly. I put a small taper on the flat so it can't pull out.

Or you can grind it deep enough to leave a shoulder for the set screw.

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Matthew Hajicek - Singularity Collaborator

Matthew Hajicek - Singularity

Posted
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Round shank carbide actually. :sofa:   That's likely the problem.  I just got a spindex for making fixture pins on the surface grinder (which is also new), so we should use that to put flats on cutters for solid holders.

 

For a one-machine prototype shop I think ER collets are the way to go.  Cycle time isn't a huge factor in my calendar-time to delivery since batches are small, mix is high, and repeats are rare.  At this point If the machine got done sooner it would sit waiting for the next program.  The heat-shrink machine alone would be a few months of my operating budget; so basically it was either that or the surface grinder.  For a larger shop I'm sure you're right.  The transition point is probably at two or three machines for my type of work, or even one machine if you're doing high volume.

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jaydenn Newbie

jaydenn

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TG and ER have the same potential accuracy and runout. That is a function of quality and not inherit of the design.

 

TG is a shallow taper (relative to ER, that is...) so you generate more clamping force BUT the trade off is less clamping "range" (.015" clamp zone)

 

ER is a steep taper(again, relatively..) so you sacrifice a bit of force but gain some range(.040" clamp zone).

 

Also, if I'm not mistaken, TG collets are a single angle collet and ER are double. That is, TG fits into the taper and the nut has a flat surface that pushes the collet in, where as an ER collet has a nose taper that matches the nut. ER require a much more precise thread and nut because of the nose taper; the nut can really pull your collet around if it's not perfect.

 

I've also heard TG collets refered to as "Tremodous Grip" collets.

 

J

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