To help you better, LAM PLAN gives you some tips for process development.
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?
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 :
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:
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.