Lepleme

There are many techniques applied to achieve a smooth and glossy surface. Lapping, grinding, polishing, honing, stripping and sanding are among the most popular methods used in industries such as metal working. Lapping is a machining process in which two surfaces are rubbed against each other with an abrasive material between them using hand movement or a machine. This method, which is based on the cutting power of free abrasive particles on a carrier or fixed abrasive particles within a composite conditioning plate matrix, is quite easy to apply. Lapping is generally applied after similar material removal processes, such as milling and/or grinding, which are more aggressive processes as an initial step. The lapping technique is based on the movement of free abrasive particles on a carrier or fixed abrasive particles in the matrix of a composite conditioning plate. While the lapping plate, to which the mixture is applied, moves beneath the surface, the workpiece rotates on the lapping plate. The uniform abrasive layer formed between the plate and the workpiece gradually removes material from all contact areas simultaneously, applying very light pressure to the workpiece. At the end of the process, when the entire workpiece has been lapped, the shape of the lapping plate has been transferred to the workpiece. For this reason, flat lapping machines can produce very flat workpieces. Depending on the lapping process applied, abrasives either roll freely or slide between the workpiece and the lapping plate. In many types of lapping, abrasive particles are fixed within the processed medium. Material removal occurs slowly due to the plate's dependent movement relative to the workpiece. Lapping can be applied to a wide variety of materials including metals, ceramics, glass and even certain plastics. It is not limited to specific materials and can be used on both hard and soft materials, making it useful for various applications. Additionally, special lapping methods can be developed to meet specific requirements. Different levels of material removal, flatness, surface roughness and dimensional accuracy can be adjusted according to target properties. This adaptability makes lapping suitable for a wide range of applications and industries.  

Application Areas

Flatness and Parallelism: Lapping is used to create flat and parallel surfaces on components requiring high precision, such as master blocks, optical lenses and precision instruments. By removing equal amounts of material across the surface, extremely tight flatness and parallelism characteristics can be achieved. Improving Surface Finish: Lapping can improve the surface finish of a workpiece, making it smoother and glossier. This is beneficial in applications where reduced friction, improved sealing and enhanced aesthetics are required. Examples include sealing surfaces of engine components, bearings and sealing surfaces of mechanical seals. Dimensional Control: Lapping can be utilized to accurately control the thickness or diameter of a part. By selectively removing material from specific areas during lapping, it is possible to achieve precise dimensions and tight tolerances. This technique is commonly used in the production of semiconductor wafers, electronic components and precision mechanical parts. Burr Removal and Surface Defect Elimination: Lapping is effective in removing burrs, sharp edges and other surface defects from machined surfaces or cast parts. It is an effective finishing method for eliminating unwanted material or irregularities remaining from previous manufacturing processes. Optical and Electronic Components: Lapping plays a very important role in the production of optical components such as lenses, mirrors and prisms. It ensures the achievement of required optical properties such as flatness and surface quality. Similarly, this technique is used in the manufacturing of electronic components such as semiconductor wafers to achieve precise thickness and flatness.

Types of Lapping

The lapping process is divided into two main types: manual/conventional and automatic lapping performed using a specialized machine. In conventional lapping, the workpiece is pressed against a rotating tool made of cast iron. The process is performed manually and some adjustment is made to ensure the workpiece moves across the tool's surface. Lapping is commonly used in glass processing, ceramic material processing and machining of fragile materials.

There are various lapping techniques commonly used in manufacturing and metal working industries. A few of the most frequently applied lapping types are:

Flat Lapping: This is the most basic form of lapping in which two flat surfaces are rubbed together with an abrasive mixture or compound between them. The workpiece is generally placed on a flat lapping plate and both the plate and the workpiece are moved relative to each other to create the lapping action. Single-Sided Lapping: In this method, lapping is performed on only one surface of the workpiece. The workpiece is held against a flat lapping plate while the lapping process takes place. This technique is commonly used for smaller parts or where only one side of the workpiece requires lapping. Double-Sided Lapping: As the name suggests, this technique involves lapping both sides of the workpiece simultaneously. The workpiece is held between two flat lapping plates and the lapping action occurs on both sides. Double-sided lapping is commonly used to achieve parallelism and thickness control. Free Abrasive Lapping: This technique involves using a mixture or compound containing abrasive particles without any fixed abrasive medium. The workpiece is held against a rotating lapping plate and the abrasive slurry is transferred to the plate during the process. This technique provides better control over the abrasive action. Diamond Lapping: Diamond lapping uses diamond particles as the abrasive tool. Diamond, being one of the hardest materials, is ideal for lapping extremely hard materials such as ceramics and hardened steel. This method can achieve very high surface quality and precision. Optical Lapping: This specialized form of lapping is used in the manufacturing of optical components such as lenses, mirrors and prisms. The lapping process requires extremely precise control to achieve the surface quality and shape accuracy required for optical applications.   Sources https://www.kemet.co.uk/blog/lapping/what-is-lapping https://www.kemet.co.uk/blog/lapping/lapping-differences-   Prepared by: Murat Soygür