Belt grinding
Belt grinding and polishing are very flexible machining processes with undefined cutting edges that use a large number of cutting particles. Depending on the abrasive belt selected, extreme high stock removal rates (1 mm and more per pass ) or super fine finishes can be achieved (Ra 0,1 µm and better).
Technology
The grinding abrasive belt is mainly guided by 2 rolls. One called the belt tension roll and one the contact roll or wheel. The contact wheel is driven, this also allows this spindle to be used for a polishing wheel. The contact wheel presses the abrasive into the workpiece. Depending on the application the contact wheel different hardness and surface texture (grooved) can be selected.
The main influence is given by the abrasive itself. The abrasive grit size depends on the application from K40 to K600 in general use. In special applications also from K24 to K1200. If high stock removal and very fine final finishes is required in a single pass, the multi head system is preferred.
Alternatively the result can be achieved by multiple passes with change of abrasive in between the sequence. Special care should be taken in determining the belt sequence to maximize belt life amd finishing results. Avoid selecting high grit size belts in the first heads to minimize heavy scratches that cannot be removed by the next finer belts in the sequence.
The main influence is given by the abrasive itself. The abrasive grit size depends on the application from K40 to K600 in general use. In special applications also from K24 to K1200. If high stock removal and very fine final finishes is required in a single pass, the multi head system is preferred.
Alternatively the result can be achieved by multiple passes with change of abrasive in between the sequence. Special care should be taken in determining the belt sequence to maximize belt life amd finishing results. Avoid selecting high grit size belts in the first heads to minimize heavy scratches that cannot be removed by the next finer belts in the sequence.
Applications
The belt grinding and belt polishing are both used to improve the finish of flat materials and profiles as well as bars and tubes such as hydraulic, pneumatic and pressure cylinder; Axles, Calender rolls and billets; Engine components, stamped and sintered parts. For scale removal or linishing and sanding before and after coating.
Materials
Stainless steel, steel, Super alloys, copper, brass, aluminum, titan, zirconium, inconel, incoloy chrome surfaces, coatings, ceramics and synthetics all the way to paper tubes and cores.
Characteristic
Due to the wide range of grinding media, this method is equally suitable for high material removal as well as for producing very fine surfaces with excellent roughness values.
Super Finish / Nanofinish / Microfinish
Superfinish, nanofinish or microfinish are the finest surface treatment in the μ-range to improve the roughness. The contact ratio is significantly increased and the sliding surface is optimized by the cross-grinding pattern which creates microscopic oil pockets as usual honing. Ra values down to 0.004 µm can be achieved.
Technology
Fifteen years ago honing by stone finishing was the preferred method to achieve precise surface finishing but today more efficient Superfinish (Microfinish honing) has set new standards.
Reduced machining times and precise repeatable finishes are the result of this cost-effective process. Microfinishing achieves a uniform, consistent finish over the entire surface. Superfinishing also called Microfinishing increases the load-bearing area and thus the wear resistance.Material removal is in the range of a few thousandths of a millimeter.
Superfinishing removes the amorphous material structure, the so-called soft skin. The 0.002 to 0.008 mm thick soft skin layer is created, for example, by high cutting temperatures during stone grinding. The surface treatment is done using superfinishing film.
Superfinishing film rolls are 15 to 50 m long and available in grain sizes from 0.1 to 100 μm.
The unwinding of the tape is carried out by a speed-controlled motor. The tape is used once and so the finish result is 100% repeatable
The feed rate of the superfinishing film is adjustable. The belt passes over a contact roller made of elastomer, which is oscillating along the workpiece axis on the surface of the workpiece.
Continuous supply of new abrasives during the finishing process achieves a uniform surface finish over the entire surface.The interaction of set oscillation frequency, correct feed of the superfinish film and the speed of the workpiece to be machined produces the desired cross hatch surface structure. This way the angle of the honing surface scratch pattern can be varied. The superfinishing is carried out with the aid of coolant or oil.
All units are designed as a machine attachment, so it can easily be mounted onto conventional lathes or other machines
Applications
The Superfinish is the final operation after grinding, polishing or hard turning.
It optimizes the surfaces and reduces the processing time. Thus, pre-machined surfaces can be finished inexpensively. Typical applications include gravure rolls, film rolls, rubber rolls, rocker shafts, bearing seats, sealing surfaces, piston rods, copy rollers, pneumatic pistons, gas spring pistons, valve spools, shifter shafts, ball valves, printer axles, hydraulic cylinders and piston rods, laser engravings.
Materials
Metals, hard chrome and tungsten carbide coatings, cemented carbide, aluminum, copper, rubber, ceramics, plastics and nickel alloys.
Characteristic
Unlike grinding and polishing, Superfinish creates a cross-hatch structure on the surface.
The method makes it possible to achieve reproducibly high surface qualities on rotationally symmetrical parts with virtually any material composition.
The structure of the surface is improved in the micro range down to 0.004 μm Ra if required.
The superfinishing process allows the user to achieve virtually any kind of surface finish because only roughness peaks are removed.
As a result, no geometry changes occur on the workpiece.
Deburring
Deburring is the removal of unwanted accumulations of material such as those resulting from stamping, milling or drilling.
Technology
The deburring is usually divided into 2 process steps. Removal of the (raised) primary burr and removal of the secondary burr and, if desired, the rounding of the edges. The primary burr, if the workpiece geometry permits, is usually removed with a sanding belt or aggressive abrasive disk or brushes.
Grinding often creates a secondary burr, as a part of the material to be machined is pushed over the edge. In the following step, the secondary burr is removed using Scotch brushes or other abrasive brushing tools. Accordingly, the original workpiece geometry is restored.
The workpiece is burr-free in this case, but still has sharp edges.
If required, edge rounding can be achieved in the same work step with the correct choice of brushes and parameters (eg: to rule out the risk of injury when handling the parts).
Often, the rounding of the edges is also required for technical reasons.
For example, to protect cables or laboratory gloves.
For surface-ground parts, eg: sintered metal parts, a defined edge rounding is often required. With this method, tolerances of up to 0.02mm can be achieved.
Applications
Punchings, stampings and laser cut parts, fineblankings, milled and drilled tubes and rods, sintered parts, milled parts, car rims. shop fittings, sealing plates, fittings, trim strips, clutch plates etc.
Materials
Stainless steel, steel, special alloys, copper, brass, aluminum, sinter metals,
Characteristic
Through the use of grinding stations and planetary stations and tools - which are selected according to the application - both deburring and edge rounding correspond exactly to the specifications required.
InductionHardening
Hardening is a method to increase the hardness and resistance of the surface of workpieces to increase durability, wear, scratch and dent resistance, This is critical for items such as hydraulic cylinder rods and linear bearing bars.
Technology
Hardening reduces the wear of the workpiece. One very efficient method of hardening the surface of steel bars is using the induction hardening process.
High frequency alternating current induction coils generate eddy currents and bring heat to the surface of the workpiece. The type of induction coils used is adapted to the required depth of hardness, the diameter and the hardening speed. The workpiece heated to 900° C is transported uniformly rotating through the system at a constant speed.
The thickness of the heated layer is in the range of about 1 mm to 3 mm. Immediately after heating, the workpiece is quenched with an emulsion or water. Automatically controlled showers inject cooling media onto the workpiece. The resulting steam is removed by means of a suction unit mounted on top of the machine.
An additional tempering / annealing induction coil is used to adjust the stress in the material.
Applications
Continuous centerless induction hardening is used to harden the surface of hydraulic bars and cylinders, ball screws and other round components.
Materials
Metallic, cylindrical workpieces with diameters of 10-200 mm.
Characteristics
The LOESER technology used in continuous induction hardening produces a uniform hardness depth over the entire workpiece surface. At the same time the risk of thermal distortion ( bending ) is minimized by the spiral hardening of the workpiece. Computer controlled rotational and translational movement of the workpieces, combined with precise process control, deliver accurate and reproducible results at a high volume production rate.
Centerless Plating
Continuous chrome plating is the galvanic coating of an metallic workpiece with a hard chrome coating.
Technology
In an electro chemical process, cylindrical workpieces are galvanically coated with a chrome layer.
The bar passes a process tank in a spiral movement. The bar motion is horizontal in a centerless movement. The chromium layer on the rod is growing precise over the entire circumference and length due to this process.
The uniform rotation and translational movement of the workpieces through the system produces a very homogeneous chromium layer.
The achieved accuracy of the coating reduces the post-processing and increases the quality.
Applications
The thickness of the chrome layer applied to the workpiece is very homogeneous and, depending on the application, is between 10 and 50 μm.
Materials
Steel, Stainless steel, Metals with diameters of 16 - 200 mm.
Characteristics
The process described above reduces the required amount of chromic acid to about 40% compared to conventional systems in which the workpieces are completely immersed in a chrome bath. Thus, there is no excessive edge build-up at the ends of the workpieces. The requirements for the extraction systems are minimized, which leads to considerable cost savings. Due to this advantage, the systems are very energy efficient.
