Generally creation of very small holes 0.5 millimetres or less is defined as Micro Drilling. Micro drilling is growing at a fast pace as parts and systems are miniaturized and new products are created, especially in electronics, medical and micro-mechanical.
Many large work pieces also require ultra small holes. This process is significantly different to conventional drilling not only in the size of the holes but also in the methods used to drill them. Micro holes generally have extreme tight tolerances for depth, diameter, straightness and hole wall finish.
Breaking through the threshold of >3.00 mm diameter means that machining get much more precise needing disciplined drill room to make it work well. Micro-drilling requires very controlled work environment and tight process control.
Drilling machines that have very high sensitivity and fine resolution in the feed axis. Machines must also have very precise spindles capable of high-speed rotation with low dynamic runout <0.003mmm or lower.
Specialised machines have been developed specifically to perform micro-drilling /micro-machining operations.
Generally micro drills have a common shank with shanks ranging from ~3 / 3.175mm /4mm diameter (sometimes 1.00/1.50/2.00) and shank sizes and overall lengths ranging from 25/30/32/35/38/40/45/50 mm.
Tools should be held in ultra precision collets.
Key to efficient micro-drilling is the drill’s ability to produce even wear across all cutting edges in order to reduce cutting forces required for chips evacuation and prevent chips from welding themselves to the flutes. Therefore, the surface finish on these drills must be ultrafine.
Matching the material to be drilled to the cutting tool is similar to conventional drilling operations except that in micro-drilling, the cutting edges must be very sharp and dead on centre.
Micro-drills do not have structural integrity to punch/bull their way through a workpiece. Micro-drill makers influence the performance of tools in different materials by varying the geometry of the drill, tool materials and Coatings. Once the process basics for micro drilling are in place, feed control, spindle and tool holder runout; cutter material and geometry; and cut data — micro boring and reaming to hold <3 microns tolerances are reachable.
Deep hole drilling with micro-tools is improving as the cutting tools machines and techniques improve. Possibilities range from l/d of 10 /15 which are standard to even 30/40 are possible under certain application conditions and materials with peck-drilling.
Center drills with a reverse diameter tolerance (i.e. +0.004 mm/ -0) rather than the standard tolerance in the opposite (negative) direction provide a pilot hole for deep drilling operations. This operation allows the long and structurally weak drill to enter a slightly oversize hole to prevent bending and breakage.
Thru Coolant drills are available from 1.00mm and even down to 0.50mm drill dia from AXIS and few high end manufacturers. Micro-drilling can be used very effectively in volume production both in workpiece quantities and number of holes per part with quality Micro-drills
Handling Micro-drills that are smaller than a human hair requires not only new machining process considerations, but understanding the need for gentle handling of these fragile cutters. Using micro-drills is learnable skill which comes with experience.
AXIS NexGen: Innovation in Ultra Micro and Micro Drills
AXIS has extensive experience, technological expertise to craft wide range of high precision micro tools with unique geometries, designs and close tolerances to machine emerging / challenging job materials and which demand extremely close tolerances.
AXIS NexGen Micro Drills encompasses application specific drill designs, ultrafine tungsten carbides, controlled edge preparation and balanced micro geometries, with high performance NexGen coatings and MMP super finishing.
AXIS Micro Drills start from ø0.020mm (20 microns) to 3.00mm and ultra-close tolerances and extremely fine finishes hitherto unseen.
Family of 6 NexGen micro drill variants are designed specifically for machining steel / ci, stainless steels, copper / brass, aluminium, titanium, plastics / soft material, graphite / green ceramic and hardened steel applications in micro mechanical, automotive, medical, horology and aerospace domains.
Stainless steel: This material is commonly used for manufacturing parts for the aerospace, medical, and horology industries. This is difficult to machine material for which we have optimized range of Micro drills with balanced geometries, edge stabilization, ultrafine carbide grades and NexGen coatings.
Aluminium: To meet the machining needs of this aluminium we have developed the geometries with wider chip space and polished flutes.
Plastic and Soft materials: Plastics are finding more use in day-to-day. Considering the low melting point of this material and burrs issue can be faced while machining plastics. So selection of perfect tool is very important. AXIS has special geometries with optimized point angle, sharp cutting edges and polished flutes.
Graphite / Green Stage Ceramic Machining: As graphite is abrasive and brittle in nature, resulting into difficult machining. Graphite Electrodes used in EDM need to be precise and accurate. AXIS offers micro-drills with close tolerances and highly uniform CVD Diamond Coating resulting into high quality and precise machining of graphite electrodes and green stage ceramics.
Hardened Steels: During the machining of hard parts tools wear is very fast because of high heat generated during machining. Its machining requires special edge stabilisation treatment on cutting edges along with strongly adhesent coating which can reduce heat generation during machining. Our in-house smooth coatings and special capability to ensure controlled edge stabilisation adds an additional feature to AXIS micro drills to meet exacting application needs.
Coolant Hole Drills: Super finishing on flutes for faster chip flow, special margin which support and guides the drill while drilling long holes, curved cutting edges for small and curled chips , special flute form for superior chip flow, through coolant holes at optimised locations to ensure correct pressure and volume of coolant to cutting edge are hall mark of AXIS coolant hole drills. AXIS offers thru-coolant micro drills from 0.50mm diameter. Team AXIS with more than 30 years’ experience in micro drilling offers solutions and application advice for optimized performance.