So if something happens and you have all your parts drilled, and you run out of form taps, you are stuck getting more. The hole drilled is considerably larger than the standard cut tap drilled hole. Since the hole drilled for form taps is larger than for cut taps, the material displaces into the flutes of the tap, thus becoming smaller. Too large and the final minor diameter will be too large, and not in tolerance. Too small and the odds on breaking the tap go up dramatically. If the hole is incorrectly sized you can have problems of two kinds. The tolerance you will need to hold is tighter than for a cut tap. The other, lesser problem is controlling hole size. The acids must reach the entire length of the tap to dissolve it, and all you really have access to is the very top, broken surface. Some of the acid removal methods sort of work, if you can find one that will not attack the aluminum enough to damage the part, but again the lack of flutes makes it mostly impractical. You have a hollow tap, but it will still be stuck. Since there are no flutes, even a sinker EDM burning a hole in it will not leave just pieces stuck in the part threads that nearly fall out on their own. One is when a tap is broken, it pretty much makes scrap of the part. There are two downsides that I will mention. It is smoother, stronger, has no chips to worry about. Overall, the thread produced is superior to a cut tap thread. We use the charts above to estimate these numbers.I cannot speak to the use of form taps in plastic, but I have form tapped literally thousands of holes in both 60 alloys. (DEPTH = 30% of the diameter of the tool plus the thickness of the material)Īdd in time for potentially dull tooling, etc.Īdd in time for less than adequate machine thrust, etc. MINUTES multiplied by 60 = SECONDS it takes for the process. Generally, this is the calculation we use to figure out the time it will take to perform a process: We can help you lower your cycle time when drilling holes in a part or multiple parts. (watch those clearance, rake and lip angles as well as rough surfaces, etc.) Tools that were manufactured or sharpened incorrectly.Too deep of a cut without proper chip removal – Chip packing (try peck drilling, air blast or coolant through the tool options, etc.).The tool is not rigid enough (try drill bushings or guides, guide rods on the drilling machine, etc.).Inadequate coolant or lubricant (at the tip of the tooling).Inadequate coolant or lubricant (overall for chip removal, rubbing, etc.).Hard spots in the material such as scale, silica, imperfections, etc.Improper cutting tool type or material (HSS vs TiN vs Carbide, etc.).Note that excessive tool wear or breakage is often caused by: Check with tap your tooling manufacturer for specific requirements and limits. We suggests a minimum of 2-3 times the horsepower of drilling for standard tapping processes and higher numbers for flow or roll form tapping. Tapping generally runs at around 1/3 to 1/4 the RPM of drilling. Check with your reamer tool manufacturer for specific requirements and limits. The last thing you want is to stall your machine or motor. AutoDrill suggests the same horsepower rating in case the hole is undersized, etc. Reaming generally runs at 2/3 or less the RPM of drilling. Check with your drill tooling manufacturer for specific requirements and limits. It is often helpful to take a heavier cut in stainless than a lighter one to keep the tip of the tool in “cool” material rather than near the surface that was recently heated up by the last pass of the tool tip. It will almost immediately ruin the cutting edge of your tool. However, in stainless, the RPM rate must be decreased significantly more. Stainless steel does not dissipate heat easily. In most metals, the RPM rate can be decreased to 25% of what is shown above to drill without coolant. The process of drilling holes in metal or similar materials without coolant is possible but not suggested. For instance, many people drill 1/16″ holes at less than 10,000 RPM with no problems. If the chart above specifies a higher RPM than your machine is capable of, it should not cause a problem to run at a lower RPM. A typical drill press often has an RPM limitation of between 2000-3600 RPM.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |