CADEM CNC software reduces CNC cycle time and down time, and improves the efficiency of CNC training in CNC training centers and skill development institutes.
47. Morse tapers on CNC tools. Morse taper – the inside story A taper is of course the best way of achieving concentricity between two components.
Mating cylinders necessarily need to have a clearance, the male being of smaller diameter than the female. This clearance causes an axial shift between the parts. Mating tapers with the same angle, on the other hand, are forced to be on the same axis. Holding tapers are of two types – self-holding and self-releasing. Reamers with Morse taper shank (I wonder if people not connected with Mechanical engineering think “These Mechanical engineering types are obsessed with sex, even at work – disgusting people”).
In self-releasing tapers, the male will not stick in the female without a drawbar holding it in place. Morse tapers come in 8 sizes, #0 to #7. While browsing the web one day I found to my surprise that Morse tapers are commonly used in orthopaedic implants too, like in the artificial hip joint in these pictures. Work hardening - how it affects CNC machining. Work hardening, and how it affects machining Work hardening is the process of a metal becoming stronger and harder by plastic deformation, due to changes in the crystal structure of the material.
When you bend a piece of wire back and forth a few times, it becomes harder to bend at the same point. This becoming ‘harder to bend’ is work hardening. Some metals like low-carbon steel, pure copper and aluminium can only be strengthened this way. They are deliberately work hardened by hammering, rolling or drawing. Copper being work hardened. Increasing CNC machining capacity at low cost. Increasing capacity – buy a machine or reduce downtime on existing machines ?
Tough decision for a CEO ! Increasing CNC machining capacity Downtime on the shop floor can be up to 30 % because of poor work ethics and system problems (see this earlier post of mine). If I have 10 machines on my shop floor and I want to increase machining capacity by 10 %, I have two options: Option 1: Buy another machine. Option 2: Reduce downtime by 10 %. How a bad CNC machine can increase your power bill. How a bad machine increases the spindle load and your power bill Machines of two different makes may look the same, and we wonder why one costs so much less than the other.
The reason may be that the cheaper machine is badly designed, made with cheaper components. The poor design and build quality increases power consumption in anything that is consuming power – spindle motor, axes motors, coolant motor, chip conveyor, etc. This little explanation is only about how a poor spindle drive train can result in a higher spindle load and bigger power bills.A poorly designed spindle that is heavier or has a larger diameter than necessary, has more moment of inertia, requiring more power to rotate it.Poor bearings result in increased friction as the spindle rotates, and more energy to rotate the spindle.Poor belt design and belt quality increase power consumption because of underbelting (belt with not enough load capacity) or overbelting (belt with too much capacity).
Grooving on CNC lathes - dwell at the bottom. Grooving on CNC lathes – why you need a dwell at the bottom The grooving insert moving into the groove is actually moving along a spiral path.
Modifying cutting speed for required tool life. Modifying cutting speed for required tool life Recommended cutting speeds in tool catalogs are for a tool life of 15 minutes.
This means that with these parameters the insert edge will have to be changed after 15 minutes of contact with the workpiece. E.g., if the contact time is 3 minutes in rough turning, you will have to change the rough turning edge every 5 parts. If you want a different tool life, multiply the cutting speed by the appropriate factor in this table: Example: If the cutting speed recommended in the catalog is 200 m/min and you want a tool life of 45 minutes, the multiplication factor is 0.75. 40. Face mill angles. Do face mill angles matter – square shoulder, 45 degree, what’s the big difference ?
A face mill is subjected to two components of force – a radial force and an axial force. The radial force causes the arbor to bend sideways. It causes vibrations, poor surface finish, and reduces the life of the bearings in spindle. Face milling cutter – forces Effect of radial force on face mill. 39. Heat shrink holder. Heat shrink holder The heat shrink holder has a cylindrical bore which holds a tool with a cylindrical shank, like a side lock holder.
The problem with a side lock holder is that it needs a clearance between the tool shank and the bore, typically 10 microns. When you clamp the tool with the side screw, the tool gets pushed to the opposite side of the bore and is not central, thus causing runout. The moment you have a runout you have imbalance, vibrations, and all the related problems like reduced finish, reduced accuracy and lower tool life. Side lock holder clearance. 38. Threading – determining depth of cut. Depth of cut in Threading – painful problem, with a simple solutionThread cutting often fails because of improper depths of cut.
Too high depth of cut causes excessive load on the tool and part, high tool wear, and poor part quality. Too low depth of cut causes high cycle time and work hardening. Calculating the depth of cut involves a simple formula, but is not done on 90 % of shop floors. Most programmers have a thumb rule that has no scientific basis. 37. Inserts coatings – simple explanation. Insert coatings and your shoe’s sole – what’s the connection ?
A shoe must be comfortable on the feet, made of material that is soft and that moulds itself to the shape of the foot. Leather has this quality, so we make shoes out of leather. But this same quality of softness causes problems on the sole, which wears out fast. We want the body of the shoe to be soft, but the sole to be hard. 36. Reduce downtime in breakdowns. Is your machine sleeping a lot due to breakdowns ? Typically, when there is a machine breakdown on the shop floor, this is what happens: The operator goes searching all over the shop floor for the supervisor to report the problem, can’t find him, and returns to his machine. The supervisor, who was in Process planning for a clarification, returns after 15 minutes. The operator reports the problem, and the supervisor then goes to the Maintenance department to report the issue. There’s nobody in Maintenance because everyone is attending to problems elsewhere. He finally finds someone after 15 minutes, reports the issue.
35. Threading – using the correct Anvil. Anvils (alias shims) in threading tools – small things that make a big difference A thread is actually a groove cut at an angle, a helical groove. The angle of the threading tip must match the helix angle of the groove, so that the clearance on both sides of the insert is equal, and one side doesn’t rub against the thread profile. Unequal clearances cause unequal cutting forces and tool wear, and result in poor dimensional accuracy and surface finish. The insert is therefore seated at a sideways angle on an Anvil, or Shim – some manufacurers call it an anvil, and some call it a shim. 34. Eliminating trial part rejection. Eliminate trial part rejection and increase profits This is one of those “Oh, this is how we’ve always done things here” areas of a shop floor system. When we machine a batch of parts with a new CNC program, we always assume that a couple of parts are going to get rejected while trying out the program, because of program mistakes.
33. Cutting params selection – turning. The right cutting parameters can reduce cycle time, drastically Even animals use tools properly, but humans on a typical CNC shop floor totally misuse cutting tools. Crow using a stick to get ants, and Chimp using a stone to break a nut Using the right cutting parameters can reduce cycle time and machining cost.
For example, if you are using a cutting speed of 100 m/min when you should be using 200 m/min, it means your machining time and machining cost are twice what they can be. The reality on most shop floors is that we select any available insert that fits into the holder that we are using, with some cutting parameters that WE are comfortable with, not what the tool is comfortable with. Every cutting tool manufacturer’s catalog tells you what insert grade, chip breaker geometry and cutting parameters to use. This short document shows you how to select the insert grade, chip breaker geometry and cutting parameters for Turning and Boring. CNC software. 32. Machine downtime – trivial reasons. BIG Machine downtime can result from SMALL reasons, and ruin your ROI This is a real story from a shop floor that uses our LEANworks machine monitoring software to track their machines, mostly VMCs and HMCs.
Among other reports, LEANworks gives a report of downtimes and their reasons. The shop Manager kept noticing that every machine reported periodic downtimes for ‘waiting for tool’ in every shift. The downtimes added up to something like an hour every day, on every machine. He walked over to the shop floor, asked a couple of operators what this was. 31. Coolant-what is it, and why use it ? 30. Why Diamond cannot cut steel. Why you cannot cut steel with PCD tools PCD (Poly Crystalline Diamond) tools are made of diamond, and diamond is essentially pure carbon, with atoms arranged in a cubic crystal arrangement that makes it very strong. 29. Chip shape and size, and ROI. Are you getting the proper ROI from your lathe ? Your chips can tell you ! 28. Ignorance of cutting tools. CNC milling holder - HSK taper. World Skills competition for CNC milling and turning Did you know that there is a World skills competition held every year, in a different country ?
The idea is to motivate youth to compete, to make them enthusiastic about vocational training and to compare skills and abilities of people from different countries. 26. CNC – Threading vs. linear motion. 24. Limiting spindle speed – what is it ? 23. Chip breaking in turning. Why don’t my chips break properly in turning ? Why should chips break anyway ? Improper chip breaking can result in poor surface finish, machine downtime to remove the chips periodically, and higher temperatures at the cutting edge. 22. Cutting speed and RPM – difference. 21. CNC downtime – low hanging fruit. 20. CNC milling holder tapers. Chips, and heat removal in CNC machining.
18. Carbide inserts – coatings & colours. 17. Cycle time reduction in tool change. 16. Built up edge in CNC machining. 15. Money from selling scrap. Constant Surface Speed (CSS) in CNC turning - ignorance is costly. CNC Software: Surface finish and nose radius. CNC Software: Surface finish and nose radius. Tungsten carbide tools. Tungsten carbide tools. 10. Production data on Andon boards. 9. Wiper inserts in turning.
8. Nose radius compensation in Turning. 7. Shop floor production tracking. 6. Depth of cut in rough turning. 5. Insert cutting edge geometry. 4. Maximizing spindle usage – CNC lathes. CNC turning - how exactly a long part bends. Boring bars - selection to reduce vibrations. CNC Training software. CNC milling, cnc lathe Software. Axes convention on CNC HMCs. CNC software for CNC machining, CNC training software.