What is high speed machining

[Gunner]

Scott_Bob
I'm interested on how your HSM projects are going. Are you producing different parts on the newly retrofited machine or was this dedicated to running one particular part? If your running different parts, have you achieved the same cycletime improvements or pcs/hr rates on the them? Are there any new problems you've encountered because of the HSM techniques (fixturing, tooling, coolant, etc)? Have you seen any tool life increases? How about power consumption? I've heard some shops have actually reduced their electric bill noticeably after adopting HSM techniques. I thought you might have some more info now that you've got some time under your belt.

Gunner

[camminc]

Hi Scott_Bob.

1: Are you producing different parts on the newly retrofitted machine or was this dedicated to running one particular part?
We work with single parts, multiple parts, new machines, retrofitted machines, different materials, it does not matter. We do Impact Tests which simply take readings of the cutter at the tool tip, which in a nut shell tells us the dynamics of that machine tool, giving suggested rpm and depth of cut to run that cutter on that machine. Material, max rpm, HP, number of teeth, cutter and holder nomenclature are then input to give information, by way of a custom database. This results in maximum cutting of the cutting tool in that spindle on the machine, dynamically.

2: If your running different parts, have you achieved the same cycle time improvements or pcs/hr rates on the them?
Operations can increase by 0-100%. It all depends on if the programmer uses this data each time he programs.

3: Are there any new problems you've encountered because of the HSM techniques (fixturing, tooling, coolant, etc)?
There are always problems, but in general, the same applies to all machining. Of course exceptions such as wall thickness etc are noted. Dynamically tuned cutters will out perform all other cutters in all instances.

4: Have you seen any tool life increases?
Tool life, of course increases. By using dynamics, chatter is minimized. Chatter is the most determining factor of tool life, spindle life and surface finish. Although, excessive chip loads (Forced vibration) which are mistaken for chatter in many instances. Programming makes a boo-boo and operators think it is chatter. Chatter occurs at a frequency of natural frequency of the cutter, forced vibration occurs at spindle speed frequency. Easy to detect by audio.

5: How about power consumption?
I would imagine that the better the cutting operation the less HP used.

[Scott_bob]

Scott_Bob
I'm interested on how your HSM projects are going. Are you producing different parts on the newly retrofited machine or was this dedicated to running one particular part?
Gunner

Current average cycle time improvement is 50%
Smallish lot sizes <100 pcs (JIT scheduling), we chose jobs that are common runners for us, to maximize our savings with this 1st CNC retrofit. We have a total of 40 jobs programmed for this machine now and every one of those has run more than once.

If your running different parts, have you achieved the same cycle time improvements or pcs/hr rates on the them?
Gunner

Cycle time improvements range from 10 to 300%, that's why I mention the average of 50%. On jobs with a lot of drilling, we are not going to see a lot of improvement, jobs with a lot of milling we do...

Are there any new problems you've encountered because of the HSM techniques (fixturing, tooling, coolant, etc)? Have you seen any tool life increases? How about power consumption? I thought you might have some more info now that you've got some time under your belt.
Gunner

Our fixturing, tooling, holders and most of the other main variables in machining processes have already been improved. Replacing the Fadal CNC Control was really forced on us. When we could not even come close to feeds/cycle times that the industry is showing off, we had to find out why. Anyone who makes parts for a living, I mean the guys who actually use the CNC, then inspect their work and they discover they cannot hold tolerances unless they slow the feed way down.
By the way, let me just say right here, that it is just down right goofy to think that the right RPM is all you need, to do HPM (High Performance Machining). Come on, a lot of us have many years of experience running CNC machines and I gotta say spindle speed is important don't get me wrong but, the effect on the features holding tolerance is not that great. Controlling chatter, oh yah, it's the biggest contributor. Our objective in using CNC machines is not to use them chatter free, but to make parts within specification, as fast as possible. Some day, I too will have to look at eliminating chatter; right now I don't have that problem. I guess that's because my spreadsheet does work, and I use the right RPM when I write the CNC programs.
On short run jobs, tool life is hard to measure. What we don't have is problems with tool breakage at the significantly higher feeds we are running now because we are still within the higher end of the range of each cutting tools chip load. It does help to have 6 high-pressure nozzles and good filtered 100-psi coolant flow. This was part of the upgraded Rubicon / Numeryx CNC control retrofit solution, as there was no way we were going to feed 3x faster without improving the coolant system. Power consumption is another difficult variable to quantify in a shop like ours. I could not guess what kind of savings we get here but I know it is significant.

Simply put, if we can get a given amount of work done in 1/2 the time average with a given amount of resources; power, man hours... Then we could say we saved 50% of the cost of those resources for that period of cycle up time, right?
That could add up to a lot of $'s in a hurry... ROI (Return On Investment) for us on this retrofit, was less than 3 months without considering the operational costs...

I'll try to keep you posted,

[camminc]

I guess your right, rpm is a waste of time in machining. These articles are really not there, in your world. Welcome to audio chatter recognition - The Harmonizer. See: http://www.mmsonline.com/articles/080302.html
http://www.mmsonline.com/articles/0300rt2.html

Again, drilling: See:
http://www.mmsonline.com/articles/060101.html

Again, See:
http://www.mmsonline.com/articles/010301.html

[camminc]

More on spindle speed:
http://www.mmsonline.com/articles/0300sup_analysis.html
http://www.mmsonline.com/articles/0300sup_theory.html
http://www.vtol.org/pdf/inte59.pdf

[camminc]

A database is required for information. Spreadsheets are confusing and cumbersome when it comes to large amounts of information. The database I use is custom made to provide simple screens of information of each tool, thru the convenience of a user-friendly main screen. There are screens for cutter, balance, presetting, tool crib, programming, engineering, inventory, purchasing, contacts, etc. Tracking of stability lobes, frequency response functions created from impact testing, spindle, torque, cutting forces, harmonizer screen shots, pictures of the tool assembled, etc. The database can be queried from any field of the tool, called a stackup id. Show all cutters in a specific diameter, number of flutes, machine tool used on, material of cutter, material of part, specific power used by material being cut, etc. Reports far superior to any spreadsheet. Multiple choice, user input, etc. Form views of the database may also be shown in spreadsheet form, but as I said, it is to cumbersome to view all this information in spreadsheet form. The database can be used on a network so programmers, tool crib, presetting can see just the information they need to use. Parameters can be set by the administrator so certain people in the company can edit, add, subtract information or lock out others.

[Scott_bob]

I guess your right; rpm is a waste of time in machining. These articles are really not there, in your world. Welcome to audio chatter recognition - The Harmonizer.

There you go again!
I did not say selecting the right RPM is a waste of time.
I just don't have to use your brand of dynamics to know what RPM to use. I use experience, and of course I refer to cutter mfgr's specs for the material I'm programming for, and I use Excel (spreadsheet) and it works great. I don't need a database to tell me what RPM to use.

You have said:
What is high speed machining
"Hardmill needs to get over it"?

I know it's not just me who is irritated by your lack of consideration for other people’s points of view. When you make statements excluding all other points of view except your own, you are being arrogant.

What is high speed machining

A lot of us here just believe your input has its place, just not the most important factor. Why don't you take a little of your own medicine. Get over it...

Example:
Here is a guy that is well respected in the mold machining industry.
Todd Schuett, wrote this article in 1997.

No mention of RPM as a significant variable, but a lot about the control and feed rate...

http://www.ctemag.com/viewArticle.asp?ARTICLE_ID=117
BTW, Mr Schuett is a competiter to the control that I chose, but I acknowledge his expertise in the field. You've got to be this way too if you are going to be an effective communicator.

Sincerely,

[camminc]

Spreadsheet versus Database: The right tool
To effectively manage tooling and to maximize cutting operations in a shop, especially using higher rpms, large amounts of data are required. The reason being that with higher rpm's there may be different rpm's that can maximize cutting operations, called multipliers. You want to try and reach the number 1 multiplier. A cutter in a machine tool might want to run at 30,000 rpm x 1 multiplier (Deepest cut), 15,000 rpm x 2 multiplier (Less depth of cut) or 10,000 rpm x 3 multiplier (Less depth of cut). If for instance a machine tool can then only go 25,000 rpm and it has a cutter that dynamically wants to run at 30,000 rpm x 1 multiplier, then to run it at 25,000 rpm would be disastrous. Big problems would occur. It would be better to run it at 15,000 rpm producing higher depth of cut than at 25,000 rpm, better finish, longer tool life, higher mrr. There are many more scenarios, but this should give you an idea. This information needs to be given to the right people in the right format in the process of the operation in order to work correctly. Tool crib, presetting, programming, operator. Therefore - A spreadsheet does not achieve this by lack of design. Here is an experts words: Database vs Spreadsheet.
http://www.smartlink.net/~stevet/signal/sprd-db.htm

Note: (This makes a good comparison of controllers to dynamic's also. I have experienced both at the same time and know that dynamics - could do what controllers could not. They do work together, but controllers can not shine without dynamics being involved. Controllers (a spreadsheet) vs Dynamics (a database) I don't care what controller you use on a machine tool, sure there are good, better and etc of controller, if the controller does not include dynamics at the tool tip or audio monitoring which is at the tool itp during the cut - then it does not have all the information it needs to maximize, it is only guessing of a stable rpm by input of the programmer. (The unit that does take in dynamics in audio form is called CRAC - Chatter Recognition and Control) See:
http://www.rapid-response-consulting.com/knohow1.html

Article: Database vs Spreadsheet

I have spent several days in Beverly Hills this month training programmers on how to develop database applications in Microsoft Access. MS Access is a relational database management system for the Windows environment. This impressed on me again what a versatile programming tool MS Access is.
Yesterday, a client of mine called once again with the same problem. He has repeatedly messed up a formula in a spreadsheet he uses to keep track of jobs and man-days. So I bailed him out again.
When considered together, I thought I should address a common practice of PC users issue in this article. They use a spreadsheet to try to do database management.
This is an easy trap to fall into. The developers of major spreadsheet programs, such as MS Excel and Quattro Pro, make the bait even harder to resist. They keep adding more database-type functionality into their spreadsheet products. A spreadsheet lends itself to just throwing some data in there and massaging it later. It does not take thinking the project through and setting things up pretty much the way you want them from the outset. It requires less knowledge and experience to work with a spreadsheet as opposed to a database.
On the other hand, spreadsheets can so easily be altered that they are prone to the types of problems my client had. Not so with databases. With a database you pretty much have to deliberately change the structure of the database, or the way it displays information, etc. An inherent problem with trying to use a spreadsheet as a database is that often one day you may want to view or combine the data in a way that the spreadsheet cannot do (whereas it would be child's play for the database).
Spreadsheets are real good at calculations and crunching numbers. That is what they are for. They are not databases, and do not lend themselves to the tasks that databases do so well.
*Some shy away from databases because they do not know how to develop database applications, do not want to learn how, and do not want to spend the money to have a consultant do it. In the long run, often the productivity and wages expended on trying to get a spreadsheet to suffice outweighs what it costs to have a database developed.
Take a look and see if you know anyone who could benefit from this.

[Scott_bob]

Another good article for HSM:

http://www.ctemag.com/pdf/0203-lookahead.pdf
I wonder who taught Todd everything, well maybe not everything, he knows...

Does anyone know?

Sincerely,

[Donovan]

I know that answer. Gil for Numeryx.

[Gunner]

Our CNC control retrofit is now complete!

It's very impressive to see an 8 year old DC Servo Drive CNC machine out perform a brand new Digital AC Servo Drive machine right next to it...

I love the Rubicon (Numeryx) controls automatic feed rate motion algorithms that uses geometric look ahead, and jerk factoring to smooth out the motion.
There is no point going fast if the control cannot maintain accurate positioning and smooth dynamic feed control, speeding up when it can, and slowing when it needs to, automatically. It's really incredible. We set "one" feedrate and the control does the rest. When geometry has sharp "inside corners", feed is reduced, or with small radii. When sharp "outside corners" are detected, feed is increased, as well as when cutting straight. I have simplifed the dynamics here, maybe someday there will be some video posted. Right now we gotta make some parts...


By the way, the feed rate is constantly changing depending on the upcoming geometry, so there would be no point in determining a single feedrate that may represent an ideal "low chatter" frequency.

Scott_Bob,
Are these algorithms based on keeping a constant surface footage or are they just for controlling overshooting / Jerk? As the control alters feedrate will/can it also alter spindle speed?

Gunner

[Scott_bob]

The ansewer to the question on feed compensation is better described in this article writen by Todd Schuitt:

Another good article for HSM:

http://www.ctemag.com/pdf/0203-lookahead.pdf
I wonder who taught Todd everything, well maybe not everything, he knows...

Feed compensation, not speed compensation...
For that you'd need the dynamic "system" like what Camminc talks about...

Donovan is right, Todd worked for Gil in his early years at Sharnoa where they developed the Tiger control...
Now that team have all speciallized individually and developed their own products. Excelent products, that out perform even the GE Fanuc giant in our industry IMO.

I'm sure the Lathe guys out there could not imagine not having the constant surface speed control capabilities of modern Lathes. This motion control option automatically compensates the RPM and Feedrate depending on the Tool tip relative to the diameter of the rotating part. In other words, RPM and Feedrate are increased up to the Max RPM, Feedrate is matched to spindle speed, maintaining a constant chip load. This is extremely desirable to maximize feed rate, tool life and is key to better surface finishes, maintaining a constant chip load affects all these...

In Milling, it is nearly imposible to do the same thing. But Rubicon/Numeryx control does this better than anything else I've seen. Just yesterday, a job running on our newest Fadal with their Mp32 control, we had to slow the programmed feed rate down to F30. where this same job running on the Rubicon / Numeryx was programmed at F230. or 7x faster, Gotta make good parts...

Sincerely,