To help you better, LAM PLAN gives you some tips for process development.
Recommendations for lapping
- Isolate the machine from dust or chips from another machining centre that could contaminate the diamond abrasive and the lapping table, resulting in deterioration of the surface finish of the workpieces.
- Cover the machine between uses to avoid pollution.
- Periodically check the condition of the abrasive dispensing devices: the MM909 dispenser and the 815 double nozzle - replace the dispensing tubes every 6 months.
- Only use SPYLAP® LAM PLAN ceramic rings on NEW LAM M'M' platens.
- Before fitting them, make sure that the studs are not damaged to avoid damaging the plate during the break-in cycle.
- Clean the rings periodically (once a week or before a long stop).
- Change the rings when the active part is completely worn out.
- Check the flatness of the platter every hour of running-in with the micrometer ruler. The flatness of the plate must be between a maximum convexity of 0.02 mm and a maximum concavity of 0.02 mm.
- If necessary, level the lapping plate with the DIABLOC system.
- In case of high production, high material removal and/or large lapping surface, LAM PLAN advises the use of a built-in cooling plate.
- This innovative system allows to control the heating of the plate and thus to increase the intervals between the lapping operations, guaranteeing a constant production of your parts in quality and quantity.
- Grooving the lapping plate, if it is necessary to increase the cutting power, the grooves are of the order of 0.2 to 0.3 mm deep on a 3 to 4 mm pitch. LAM PLAN offers on request grooved versions of its NEW LAM M'M' and single component 2000 series platens.
- Before each prolonged stop, clean the plate properly to avoid mud accumulation. Clean with alcohol or petrol.
- Avoid blows to the platen when placing heavy parts or rings. Avoid heavy scratches from lapping undeburred parts. These accidents can damage the platen and impair its performance.
- This is the amount of abrasive available on the substrate, formed by the spraying of the diamond liquid and the lubricating fluid.
- Keep the abrasive film neither too dry nor too wet to ensure a good compromise between material removal and the flatness of the board.
- An abrasive film that is too dry gives good stock removal, but causes the lapping surface to heat up, which is detrimental to its flatness.
- An abrasive film that is too wet maintains the flatness of the plate, as it does not cause overheating, but limits material removal.
- Diamond fluid: shake the bottle well before pouring it into the MM909 dispenser, the agitator option is recommended when using fast settling abrasive products (e.g. SERIES 241P).
- In order to limit the temperature rise due to the running-in cycle and to control the consumption of diamond fluid, a lubricating fluid can be used. Only use the fluid recommended by LAM PLAN that is compatible with the diamond fluid.
RESULTS ACHIEVED AND CONTROL
- Roughness: surface condition resulting from lapping measured with a roughness meter. The NEW LAM M'M' YELLOW plate will provide a surface finish close to 3/100 µRa on treated steel parts.
- Flatness: LAM PLAN diamond lapping provides a sufficiently bright surface for direct control of flatness. This geometric dimension is measured optically using a monochromatic lamp and an optical gauge.
- Material removal: Material removal is conditioned by the size of the abrasive grain, the hardness of the table, the load applied to the parts and the cycle time.
- As the first three parameters are locked in by prior tests and a method, only the duration of the lapping operation will vary the material removal. This value will be measured with a measuring column.
CLEANING OF PARTS
- At the end of the cycle, the lapped parts must be cleaned to remove sludge and traces of abrasive and to allow optimal control.
- The use of LAM PLAN NEOLAP® products guarantees easy cleaning of the parts using a conventional or ultrasonic washing bath.
The choice of the cutting disc is essential. It will depend on the hardness and ductility of the material to be cut as well as the fragility of the coatings that make it up.
How to choose a cut-off wheel?
- with Al2O3 abrasive for ferrous materials,
- with Sic for non-ferrous materials,
- See the selection tables for cut-off wheels.
The harder the material to be cut, the softer the bond of the wheel should be. For example, for precision cutting of hardened steel with a hardness of 50 HRc, we recommend an H2 or LAM PLAN BLUE cut-off wheel with a relatively soft bakelite bond.
Recommendations for use
Make sure that the lubrication is correct. This will avoid any risk of overheating. This can lead to structural damage. For all metallographic cuts, LAM PLAN recommends the use of cutting fluid 721 in combination with the CUTLAM 1.1 or 2.0 cut-off machine with optimised coolant.
Coating allows you to limit the edge effects during the polishing stage. In addition, this operation will allow you to :
- During manual polishing: to facilitate the gripping of the sample
- During automatic polishing: to gather several samples in a specimen holder in optimal clamping conditions.
Recommendations for use
Before any mounting procedure, degrease the specimens so that the resin can be applied to the contours of the part. Ensure that there are no burrs from cutting. If necessary, deburr the corners of the specimen on sandpaper.
How to choose a resin?
Choose a resin with a hardness close to that of the material to be coated.
There are two families of mounting resins:
Cold: These are recommended for preparing individual samples. It only requires the investment of resins and mounting moulds.
Hot: For laboratories that prepare a large number of samples. With this process, the size of the mounts is uniform. The resin is cheap but requires the investment of a PRESSLAM mounting press.
Procedure for cold mounting
The sample is placed at the bottom of the mould, it is recommended to use clips to keep thin samples on the edge. Proceed to mix the resin components respecting the doses indicated in the technical sheet. Mix gently to avoid creating air bubbles. Pour the resin into the mould to the desired level and allow to cure in the open air or in an M.M.806 pressure vessel to remove any bubbles or pores.
The mounting time is generally around 15 minutes except for RESINA CRISTAL (epoxy resin) which is around 8 hours.
Procedure for hot mounting
The sample is placed on the lower piston of the mounting press. The mounting is made possible by pressurising the resin and sample together and by applying heat. Then, a cooling phase with water will finalise the hardening of the resin.
It should be noted that the quantity of resin must be optimised. It depends on the volume of the part to be coated.
Polishing is defined as the use of increasingly fine abrasive grains to obtain a surface ideal for microscopic observation.
This procedure can be divided into two phases: PREPOLISHING and POLISHING.
The objective of this step is to obtain a flat surface on the samples. For this purpose, so-called "fixed abrasive" supports are used:
- for soft materials, silicon carbide abrasive paper.
- For other materials, the CAMEO®DISK PLATINIUM disc range.
After grinding, there is a transitional work phase, carried out with CAMEO DISK SILVER OR GOLD. These are substrates without abrasive fillers, but which guarantee very good flatness. A diamond liquid is used as a free abrasive on these two discs.
The aim of polishing is to eliminate the damage left by the previous steps. We advise you to use a diamond abrasive, of decreasing size, which will be sprayed on softer and softer polishing supports such as 2TS3 (woven) or 4FV1 (felt), until a perfect polish is obtained.
It should be noted that on certain materials which are generally very ductile, colloidal abrasive will be used instead of diamond abrasive.
LAM PLAN is able to provide a complete range of manual or automatic polishing machines in central or individual pressure mode.