|Drilling and Tapping|
Paper And Fabric Grades
A standard high-speed drill with lips backed off to provide plenty of clearance is satisfactory for all Atlas Fibre grades. However, for long production runs and deep holes, carbide-tipped drills give the best performance.
Drills should be retracted from the work frequently to prevent binding and excessive heating. The feed should be light and uniform and the speed of the drill should be considerably in excess of that used for soft steel. With tungsten-carbide tips, speeds may be as high as 16,000 rpm. Where possible, the material being drilled should be backed up with scrap laminate or other soft material to prevent chipping out.
In drilling parallel to laminations, extra care must be taken to prevent splitting. The material should be clamped in a vise or between plates and the drill should be retracted frequently to remove chips.
Holes 3/4” and over may be drilled in the conventional manner using radial drill presses or the counterbore method in which a pilot hole is drilled first.
Drill size - Because of the nature of industrial laminates, the diameters of drilled holes are usually .002” under the drill size. Therefore, the drill selected should be at least .002” larger than the specified diameter of the hole. If the drill is being used dull, the hole size may be an additional .002” undersize, or a total of .004” less than the diameter of the drill.
The recommendations for drilling also apply to tapping. Taps used for metal are also suitable for most laminates. Tapping heads or tapping machines may be used for production work. Collapsible taps are available in sizes over 1 ¼”.
In tapping laminate materials, high-speed or carbide taps .002” oversize should be used. The tap drill size should also be changed to .002” oversize to counteract the tendency of the drill to cut undersize. If the thread is to be used frequently, metal inserts should be used.
These suggestions reflect our experience and the experience of our customers. This is not a users manual or fabrication guide. Further, results differ based on many factors, including quality, composition and suitability of raw materials, tools and fabrication processes, and the skill of fabricators. Atlas Fibre Company does not guarantee or warrantee fabrication results on any of our materials.
Glass Base Grades
When drilling glass base grades, a carbide drill should be used. The materials can be drilled dry with the aid of an adequate exhaust system. A flood of water soluble coolant on the work and drill can be used when necessary to prevent overheating and dulling of drills. High speed, carbide, or nitrate treated drills can be used, but must be sharpened frequently. Care should be taken when sharpening that the drill is cut back far enough to original body diameter of drill. Spindle speed for these grades is 4800 rpm for 1/4” diameter drills.
The methods for tapping these materials are much the same as for tapping paper base laminated plastics. The abrasiveness may cause taps to cut very close to size, resulting in a tendency toward binding when backing out. Standard high speed steel taps can be used on short runs. For any sizeable quantity carbide taps should be used. Taps should be purchased oversize. Water soluble coolant can be used, but is not necessary if an adequate exhaust system is available.