By Simon Mannsi Project Manager, Helitronic Machines, United Grinding , Walter-Grinding Edited By Jim Benes Associate Editor Software with 3-D simulation speeds up setups and allows for review of the process before cutting. CNC grinding may be the only way to regrind tools with complex geometries. There are several reasons that shops should consider CNC tool grinding, including that it provides the ability to produce high-quality, long-lasting tools and allows for flexibility and control of the process while saving them a ton of money. Because in-house tool grinding is not part of shop’s core competency, careful analysis is necessary to be sure in-house grinding can be justified.

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Shops must be able to dedicate a fulltime operator to run the machine. Training operators for CNC tool grinding is not difficult, but about five-years experience with CNC machine tools is required. And, operators do need to have a good working knowledge of tools. Shops can justify a CNC grinder based on financial or flexibility considerations. From a financial standpoint, a shop running standard tools needs to be spending at least $200,000 per year on the tools to be reground. However, shops that use special tools or change tools frequently can regrind these quickly with in-house capability.

Advantages of CNC grinding In-house tool grinding with manual machines presents several challenges. For instance, multiple machines are needed to grind one tool.

A fluting machine, an O.D. Machine and a pointing machine might be needed to grind one drill. This means multiple setups, whereas a CNC grinder needs just one setup for a complete grind. Similarly, a CNC grinder requires less floor space than multiple manual grinders. Another concern is the workplace fouling created by the carbide dust that is generated in unenclosed manual machines. Most importantly, manual tool grinding relies on the skill level of the operator, and this is a dying art.

Finally, manual grinding takes much longer than CNC grinding. The data in Table 1, supplied by an automotive manufacturer, compare manual versus CNC tool-grinding times. As the tool geometry gets more complex, grinding times increase dramatically. A problem with outsourcing is a lack of flexibility. For example, shops can run into overly long regrind times if they are running tools with unusual geometries, or they are involved in development work where tool features need to be quickly tweaked. Also, shops have little control over the quality of outsourced tool regrinds. When shops outsource, the regrind shop determines the scheduling of jobs to be run, so a shop may find itself at the end of a long line.

Shops that grind in house have control over the priority and scheduling of tools to be reground. The case for consistency Not only is CNC grinding faster than manual grinding, it also makes better, more consistent tools because it does not rely on the skill of the operator. Many high-speed machining centers use tools with complex geometries, such as drills with different helixes on each tooth, or with helixes that vary along the tool. Such tools are difficult, or impossible, to grind manually with good results. With many software options, newer CNC machines can easily grind complex tool geometries. CNC grinding of a drill ensures that there are no deviations in the diameter, space between teeth and radii of the tool so each tooth will cut evenly.

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Inconsistencies in these features can result in extra stress on individual teeth leading to reduced tool life. Tool consistency allows for long, uninterrupted runs, and tool changes can be scheduled to realize the full life of the tool. Also, the required number of tools for a job can be accurately determined from production schedules while tool inventories are reduced.

Better tools produce less heat and vibration so machine tools last longer and require less maintenance while producing better surface finishes. Also, CNC grinding allows for the use of tougher tool materials allowing high cutting speeds and producing finer finishes. Usually, manual grinding is done dry, while CNC grinding offers many coolant-delivery options The use of highpressure coolant prevents heat buildup on the cutting edge to allow for increased cutting speeds and extended tool life.

Speed reduces cutting costs The most important factor in achieving cost-effective productivity is cutting speed, rather than tool cost or tool life. For example, industry data has shown that a 30 percent decrease in tool cost results in only a one-percent savings in cost-per-part to produce. Similarly, a 50 percent increase in tool life also results in only a one-percent savings. However, a 20-percent increase in cutting speed (even with a 50 percent increase in tool cost) results in a 15-percent drop in cost to produce each part. High-quality CNC ground tools can easily result in a 20 percent increase in cutting speed over speeds possible with manually reground tools. Costs of outsourcing The total cost of outsourcing tool regrinding involves the cost of production tools, plus the cost of spares to maintain production while the tools are being reground, plus service and shipping costs and, importantly, the cost of lost production in the event of a delay in regrinding service. These costs can add up to a significant annual burden.

For example, consider a 0.5-in. Long, square, carbide endmill running on 20 spindles that cuts for four hours during each eight-hour shift for 250 days per year. With a 10-day turnaround time for regrinding, this tool would cost $206,000 per year to maintain by outsourcing tool grinding, Table 2. Annual cost to maintain this same tool running on 40 spindles, with a shorter duty cycle of two hours would skyrocket to $824,000. Costs of in-house CNC grinding The real cost of in-house tool grinding — including machine costs, operator costs and shop overhead — can be considerably lower than the cost of outsourcing tool grinding (Table 2).

For example, the cost per hour of acquiring and running a $240,000 CNC grinder — considering typical costs of depreciation, interest, floor space, energy, maintenance and machine consumables — is $28.09 per hour. Typical operator-associated costs amount to $18.33 per hour, for a total of $46.42 per hour to run the CNC grinder. In the previous examples of a 0.5-in. Long, square, carbide endmill running on either 20 or 40 spindles, annual total in-house costs of tool regrinding are about one-fourth the cost of outsourcing regrinding.

Tips for choosing a CNC grinder Be sure the machine has the versatility to grind all current and future tools you might need. Make sure software is easy to use and has 3-D simulation. The machine should be able to be set up offline so tools can be ground while setting up another job.

When choosing a machine for regrinding tools, be sure it is also capable of also manufacturing them and has the required power and coolant pressure and capacity. Be sure the machine is rigid and accurate. Heavy machines are not necessarily rigid and moving heavy masses causes wear and it’s slow. Be sure you can share software programs with outside regrinders. Service and support are critical.

Be sure local training and service are available.

No i dont use P4 for the moment, its easier and faster to use P32 and you also have more power for grinding complex profiles i think you have a limitation in P4 that the steptool only can get bigger in diameter and that limits me, the dxf loading is a nice thing since all drawings comes in dwg or dxf files, so its just to cut out you profile from the drawing and load it into P32 and your almost done. On the other hand in P4 you can gash the inside rake angle on the differnt steps so you dont get negative rake angle on the smaller steps in diameter, but there is for sure more nice things in P4 that i dont know about. If you have any problems just tell me, and i would do the same. Been using these machines for 7 years now.one mini production.one power-r and one power-r with disc loader.use pkg's 1,2,3,4 and beginning to use pkg 32.we mfg alot of high performance drills and step drills using pkg 3.and use pkg 4 for our form tools.I've manufactured 2-flute ballnose tools on pkg-4 holding a.0394 dia.

+.0000/.0001 and a length of.0669 with the same tolerance intersecting into a 59 degree 34 minute +/- 5 minutes(included) in lots of about 50 at a time.using our mini production (with glass scales) and very nice univel metal bonded diamond wheels.I'd really like to get more in depth into pkg 32. We have two of them in the shop, power 500 and vision. We also have toolcheck. Not my favorite machines around, bit of a PITA to calibrate, and fix when they break. I suggest making a hard drive clone, and replacing CRT monitor for some generic LCD on power. I might have schematics for attachiing MPG somewhere if anyone cares, always wanted to do it, just never had time. Also if you're using NT4, update to SP6, and newest walter software.

They finally fixed that silly network set up they had going there. We also have about 40 Rollomatics, if anyone wants to talk about them. We grind carbide only. I'm interested in knowing what packages everyone uses. I'd like to know a little more about using the corner radius offsets in package 1. I have successfully been able figure out how to blend the radii on the end, but once in awhile still having some trouble blending the radii on the diameter of the tool.

I've attempted to use the offset under the Corner Radius page under the Geometry menu. With little to no success. Any help is appreciated Don still having trouble with the rads? Are you using mgm grind or hollow grind? Hi, well I guess I have you all beat, I have been on a walter now for about 14 years, and we still run the first machine we purchased, its a 45 helitronic.

We also have a first generation 400 power machine still running dos (thats all it can run) and a larger newer power production, or at least thats what they called it when it first came out, now I think they would class it as a power r, and we also have the first diamond machine in north america as well as a helicheck that aint worth a pinch of beens. Packages, when I do run the machine, I love to use expert mode, but I use that, p1, p3, p4, a little p7, & p52 (diamond machine) and the occasional p2, I hate p2 and I dont do much in the form or ball ends or corner rads, they are always a pain in the rear to get perfect blends on these machines. Never learned p32 but I hear its pretty cool. We also run a rollomatic, I like this machine for basic tools and large runs, but the walters are great for smaller orders and tricky tools. Cool site you guys have here, I like it;). Do you use your rollomatic for micro tools?

I heard they are good machines for small tools? The smallest tools i've made on a walter was a.032 ballnose tapered endmill and i've made 0.032 drills. I use pk2 and pk32 all the time, i could give you pointers on blending the rads and balls if you'd like, but if you've been doing this 14yrs, you probably would'nt want to hear it. I've only ever met 1 person on the walters longer than myself. I'd love to share ideas.

I spend most of my time looking after guys running the machines, trying to keep a handle on things, and fixing the machines when they break down.which lately has been quite frequently:( I only really get into it anymore if its something tricky, or if I'm training one of the newer guys on something, or if its got to be done YESTERDAY LOL. For the most part, I use pkg.3, 4 and expert mode. I'll be honest with you though, when it comes to blending a rad on a ballnose, or corner radius endmill, I suck at it because frankly, we seldom do that sort of work in our shop so I never remeber the little tricks, but thats where cybergrinding comes into play, its easy to see what to do when you can over correct it by a mile to see what the outcome will be. Hell, I cant imagine running efficiantly without cybergrinding anymore, especially for something out of the norm, or tricky, which is why our older machines almost never get used for manufacturing anymore, mostly just regrinding on them. As for Rolly, we like Rolly for small stuff, but so far I think the smallest tools I have done are around 1mm for some step drills, and some 2mm 3fl center cutting endmills. I wouldnt even atempt that on the Walters, not with the spindles in those machines, they are terrible.

How long have you been at it on the Walters? I have been using Walter Grinders for 12 years now. We curently have 9 machines. 1 HMC 600 Vision w/ Loader, 4 HMC 500 Power Productions with cyl. Loaders, 1 HMC 500 Mini Power, 1 HMC 400 Power and 2 HMC 400 Powers w/ loaders, there are only a few of these our there.

My software experience is wide. P1,P2,P3,P4,P5,P8,P32,G code or Flex Prog,expert mode and Tool Studio. I have also done a lot of maintenance on all of these machines. I enjoy programing special projects and trouble shooting problems. I would be happy to help answer any questions that I can. We are also allways looking for operators/programers for solid carbide specials. I have 30 years experience grinding cutting tools on manual machines.

I have about a year on some Huffman 85s. We have 5 Walters and I have been able to get about a months training and a month of running them. I would love to get more time but always need to fix tools on the manual machines that the guys on the cncs say they can't get. Anyway the question I have is about tapered end mills with a radius on the corner. I am trying to figure out how you get the angle and diameters to come out right. I have tried setting up the tools with diameters called out and the length. The angle doesn't even come close.

If I call out the angle and give the diameter at the back or at the front nothing still is even close. I am finally getting close but am having to lie to the machine with false numbers. This is completely trial and error and wastes a lot of time and tools.

I want to learn what I am doing wrong or if there is a problem with our software. Thanks for any help.

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It would be greatly appreciated. We are working in p2. Maintenance has been out numerous time and gone over the machines. Have tried lots of combinations on the wheels and still no luck. If we put in the right numbers for d1 and d2 and put in the lengths for l1 and l2 the resulting cone angle is not even close. We are getting tools now but the numbers aren't even close to what they should be.

It does this on 4 machines and in cybergrind. I would really like to find out if we are doing something wrong or if there is something we are missing. I am trying to grind a 6 tooth solid carbide t slot cutter, 3 teeth right hand cut with 5 degrees right hand axial flute and 3 teeth right hand cut with 5 degrees left hand axial flute. Cutter is.297 wide with.020 radius on front and back of each tooth.The front and back face of cutter has 1.5 degrees dish with 2 degrees side clearence.

Can this be ground completely in p5? (first time using p5) Right now I am piecing it together with p4, p6 and p32 wich seems to be some what of a hassle but it will work for this time around. I am trying to grind a 6 tooth solid carbide t slot cutter, 3 teeth right hand cut with 5 degrees right hand axial flute and 3 teeth right hand cut with 5 degrees left hand axial flute. Cutter is.297 wide with.020 radius on front and back of each tooth.The front and back face of cutter has 1.5 degrees dish with 2 degrees side clearence. Can this be ground completely in p5? (first time using p5) Right now I am piecing it together with p4, p6 and p32 wich seems to be some what of a hassle but it will work for this time around. All that P stuff makes no sense either.:withstupialso.

Or is it just that you can't spell? Well one of my first problems is when I grind certain counterbore step drills I have been getting overtravel alarms, but I can run another piece that is the exact same and it will run. When this happens, it will completely run all the program, but when it gets to the finish pass on the counter bore (step clearance 1) thats when I get the alarm. I have tried everything I can think of to figure this issue out, but to no luck. I know that there is still alot of bugs that Walter is working out of this software and there is suppose to be a new update coming out in about 3-months. QUOTE=Walter-Master;332475I have been using Walter Grinders for 12 years now. We curently have 9 machines.

1 HMC 600 Vision w/ Loader, 4 HMC 500 Power Productions with cyl. Loaders, 1 HMC 500 Mini Power, 1 HMC 400 Power and 2 HMC 400 Powers w/ loaders, there are only a few of these our there.

My software experience is wide. P1,P2,P3,P4,P5,P8,P32,G code or Flex Prog,expert mode and Tool Studio.

I have also done a lot of maintenance on all of these machines. I enjoy programing special projects and trouble shooting problems. I would be happy to help answer any questions that I can.

We are also allways looking for operators/programers for solid carbide specials./ Hi I have been with a heletronic power walters cnc for 5 yrs.only have pkg 7 and did some pkg 4.but my question is.is there a trick in setting up program so intersecting point of radius blends the way it should.it is somewhat passible but not accurate. Ty for any ideas or help on this.be much appreciated! I Guess site needs longer explanation more characters! Should I program a false width of diamond wheel and radius size? Walters Heletronic Power Package #7 Carbide tip milling cutters.cutting brass.cutting with smear finish!! Hi, I'm working with a Walter Helitronic Power HMC 500 running on WALTER Window Mode that has just been sitting at the corner of the shop and I'm suppose to get it running to resharpen drill bits (both carbide and HSS). Unfortunately, no one here is sufficiently trained on the machine, so it has been difficult to learn everything/find useful resources.

I was hoping someone could point me in the right direction as to how to set-up the machine for sharpening drills. First step is to determine what wheels to buy and what configuration to have. How do you determine what kind of 1V1, 1A1, and 11V9 wheels you should use? Any help is much appreciated. Hi, I'm working with a Walter Helitronic Power HMC 500 running on WALTER Window Mode that has just been sitting at the corner of the shop and I'm suppose to get it running to resharpen drill bits (both carbide and HSS).

Unfortunately, no one here is sufficiently trained on the machine, so it has been difficult to learn everything/find useful resources. I was hoping someone could point me in the right direction as to how to set-up the machine for sharpening drills.

First step is to determine what wheels to buy and what configuration to have. How do you determine what kind of 1V1, 1A1, and 11V9 wheels you should use? Need a few more details on the drills before anyone can give some direction. How many flutes? Straight drills or step drills? Diameter and flute length?

Standard or Facet? If it's a simple 2 flute drill with a standard point, all you need is a 1A1 and a 6A2 (4A2 would work as well but you can't dress the inside of the diamond). You can use this setup for facet points as well, but I preferred to use an 11V9 in place of the 6A2. Details on the type of drill are as follows: - 2 Flutes - Straight - Facet point, but I would like to be able to do standard as well The sample I was given has: - 1/2' diameter - 4.5' flute length For resharpening carbide drills do you simply use diamond wheels of the same shape? I'm also interested if there is a standard relationship between drill size and the diameter of wheels you should use.

I've been searching for info for a few days now and haven't found anything explicit. Thank you for your help. You will want the following wheels to start: Spindle 1 with a short arbor: Inside wheel as a 320 grit 4' 1A1 3/8 wide, resin bond, 100-125 con Outside wheel as a 320 grit 6' 6A2, 3/8' - 1/2' face with a small (.015.020' corner break) 45deg angle on the OD. This setup will allow you to run both facet points and standard points with the same set of wheels. Keep in mind that you will need to true the wheels before grinding - especially the 6A2 as wobble on the diamond face can, and will, cause a drill to snap. I can't help with feeds and speeds as I've been out of cutter grinding for a few years and I can't remember what they were. You will also want to use a 'v' clamp with a bushing if you do not want to clamp on the flutes.

The wheel suggestions are just a starting point and over time you can play around with them to find what works best. Edit: I was going to suggest some wheel suppliers but for a second post decided against it. When I was grinding tools, we used a dedicated offline machine for truing and forming the diamond wheels. Here's a link to the machine itself. I believe they will also supply the truing wheels. Going off of memory, I believe that you need the green silicon carbide to do the truing.

Double check with your wheel supplier to verify. This machine saved us a ton of time and allowed us to put fairly complex profiles on the wheels when needed.

The only thing I didn't like about it was the vacuum on it - underpowered and undersized. I know that overwhelming feeling. Try making.5mm ribbing tools in a non temperature controlled shop, with no heat exchangers for the coolant, on a Monday morning in the middle of winter (hint: don't try - you won't accomplish anything but add to the scrap barrel).

You need the dressing sticks to open up the diamond on the wheels after truing and a lot of heavy grinding. There will be some resistance at first but then the stick will feed in easily. You might be able to use a manual tool grinder (ie Cincinnati #2 tool ginder) with a powered work head, just make sure that you match the runout between the Walter and the offline machine. You can also use a small bench grinder and attach it to the table inside the Walter (I don't recommend this if you don't fully understand how the machine operates as you can either manually move the axis or use expert programming). I hope this helps you along.