For professional friction drilling you need a suitable machine, which provides the required speed and power in kW. If operating at too low speed, the tool could overheat and the quality of the coating will be affected. If the kW power of the machine too low, it will be “stalled” because the required feed and torque can not be rendered. Furthermore, the friction drilling tool should be included in a Glowdrill collet and in a Glowdrill collet chuck with cooling ribs. This is the only way to ensure the correct fixture and a corresponding radial run-out of the tool. The cooling ribs prevent overheating of the spindle bearing of the drilling machine. After the first 10 holes, the collet should be retightened.
Selection of the appropriate GLOWDRILL tool
The selection of the appropriate friction drilling tool depends primarily on which thread should be generated subsequently produced: metric ISO-thread, metric ISO fine-thread or Whitworth pipe thread. After selecting the desired thread the appropriate friction drilling tool can be easily determined using the menus on the product page. It consists of four selection criteria, which refer to the tool design (with collar “form” or without a collar “cut”), the nominal thread diameter (eg, M8), the thread procedure (subsequent thread forming or thread cutting) and tool length (long or short).
You should ensure that at the beginning of the working process the tool is gently touching the workpiece and perforates the metal with a forward speed of 100-150 mm/ min and the required engine speed. With such forward speed the tool covers 2,5 mm per second. The depth stop of the machine with respect to the workpiece surface depends on whether the collar stops or is removed. If the collar stands, the drilling process ends approximately 0.8 to 1.8 mm above the material surface. This depends on the thickness of the material that must be processed, and thus the height of the collar. When the collar is removed, the flow drill cutting must be put flush with the top edge of material. The material should be fixed tough. So that it would not move up and down while the friction drilling tool is used.
The tip of the friction drilling tool is placed on the material. Under axial pressure, the material is heated. The tool can now penetrate the material and form the pull-through. After the appropriate depth stop is reached, the tool should be immediately driven back again, otherwise the formed material is overheated. If the collar will be removed (Design “Cut”), the feed rate should be increased significantly at the end. The worn-chip can be thrown away from the machine. Therefore, appropriate precautions (protective clothing) must be made.
Lubricants and seperating agents
The use of the appropriate lubricant and separating agent prevents adhesion of the material to the friction drilling tool. As the separating agents are highly heat resistant and matched to the machine’s materials, the tool life is significantly increased. In addition, the separating agent provides a good surface of the passage and the collar. Lubricants and separating agents should be applied regularly to the tool. When you work with steel and by manual lubrication, you should apply the lubricant at least after every 3rd up to 4th bore. For all other materials the separating agent should be applied thin over the entire length of the drilling tool before any drilling. By fully automated processing it is recommended to apply the separating agents before each hole. We recommend our Glowdrill atomizing sprayer. This sprayer is available on request.