Каталог Dormer Pramet фрезерование 2021 - 2022 - страница 313

THREAD MILLS – GENERAL HINTS

General hints on thread milling 1. Thread milling is the process of generating a thread by the circular interpolation of a milling cutter with a specific thread geometry ground around it’s periphery. 2. To be able to use a thread milling cutter it is necessary to have a CNC machine that can make circular paths. 3. Most modern CNC machines are equipped with machining cycles for thread milling. 4. Consult the manual or contact the machine supplier for information. Features and benefits 1. Thread milling gives increased reliability and tool life. 2. Threadmills produce small chips resulting in problem free threading. 3. Tolerance adjustments can be made using exact co-ordinates. 4. You can generate a complete thread to the bottom of the hole. 5. Capable of machining a wide variety of materials. 6. The same cutter can produce different size threads provided the pitch is the same. 7. Both right and left hand threads can be created with the same tool. 8. Some thread mills can also machine the entry chamfer (J200 and J205). Choosing your tool Thread milling cutters have an item code based on the type, diameter (d ) and pitch (P). The item code is the number to use when ordering your tool. 1 Always consult the catalogue to ensure you have the correct thread dimensions.

J22010.0X1.5 This thread milling cutter can be used for threads ≥ M12×1.5 (M14×1.5, M18×1.5 etc.)

Programming with Rprg

• For easy adjustment of the thread tolerance always program with radius correction.
• The Rprg value is the start value for a new cutter and is printed on the cutter shank. This should be entered in the tool memory offset.
• Rprg is based on the theoretical zero-line of the thread meaning that when you program using Rprg the thread is never oversize, but normally tight.
• This means that with a small modification to the program co-ordinates you can create the thread to the required size.

Recommendations

• Always use the correct cutting data (refer to the cutting data chart in the Product section).
• Use the recommended drill size for the thread diameter, as for conventional taps.
• For easy adjustment of the thread tolerance always start with the Rprg value printed on the shank of the threadmill.
• Use a gauge to check the tolerance on the first thread to establish if the radius needs to be corrected. The radius can be corrected 2 or 3 times before the threadmill is worn out.
• When dry machining, compressed air is recommended to help with swarf removal.
• When threading more difficult materials, it is recommended to take multiple passes.