What are the benefits of lapping compared to grinding?
A grinding process can cause high levels of stress on delicate materials as the grinding medium tears at the surface of the material, often generating a lot of heat and potentially leaving an uneven surface behind. The damage caused during grinding will also propogate through the material, often producing considerable sub-surface damage. Where a grinding pad is used on a revolving platen, it will always wear unevenly due to the difference in relative movement speed and pad area across the pad diameter, this means that the grinding effect on the sample will change during the process, reducing the accuracy of the sample and the uniformity.
Lapping is a more gentle process as the abrasive is held in a carrier fluid which passes as a liquid between the sample and the lapping plate, and as the liquid flows it performs in a more uniform manner, resulting in more uniform samples. The damage to the material during the lapping process is much lessened and more predictable, and the chance of sample breakage is much reduced.
What is the recommended Gallium Arsenide process?
Logitech have tried and tested processes for lapping and polishing of Gallium Arsenide, with machine selection dependant on material size and throughput requirements.
Some of our application process notes provide information on the process route for Gallium Arsenide.
What is the recommended Silicon Wafer process?
Logitech have tried and tested processes for lapping and polishing of silicon, with machine selection dependant on material size and throughput requirements.
Some of our application process notes provide information on the process route for Silicon.
What is the recommended Silicon Carbide process?
Logitech have tried and tested processes for lapping and polishing of silicon carbide, with machine selection dependant on material size and throughput requirements.
Some of our application process notes provide information on the process route for Silicon Carbide.
What is the recommended Gallium Nitride process?
Logitech have tried and tested processes for lapping and polishing of Gallium Nitride, with machine selection dependant on material size and throughput requirements.
Some of our application process notes provide information on the process route for Gallium Nitride.
What is the recommended Sapphire process?
Logitech have tried and tested processes for lapping and polishing of Sapphire, with machine selection dependant on material size and throughput requirements.
Some of our application process notes provide information on the process route for Sapphire.
What is the recommended Concrete Thin Section process?
Logitech have tried and tested processes for sawing, lapping and polishing of geological materials such as concrete, with machine selection dependant on material size and throughput requirements.
Some of our application process notes provide information on the process route for Concrete.
What is the recommended process for Thin Section Coal Preparation?
Logitech have tried and tested processes for the preparation of coal thin and ultra thin sections, with machine selection dependant on material size and throughput requirements.
Some of our application process notes provide information on the process route for the preparation of Ultra thin and thin coal sections.
How much abrasive should I add to my cylinder?
For most applications we recommend a ratio of between 10 and 15% abrasive to water in the slurry cylinder. The optimum ratio for a particular process can be confirmed through trials.
How to attach a pad to a flat plate?
Our polishing pads and cloths are all supplied with a self adhesive backing fitted, allowing them to be easily attached to a flat plate.
Why are some pads grooved?
Generally where sample size is 20cm2 / 2″ diameter or less we recommend that a plain pad or plate is used for processing. Where the samples are larger than these sizes grooves are required to allow lapping abrasive or polishing slurry to pass uniformly between the sample and the pad or plate.
How long will my pad last?
Pad life varies considerably depending on the pad type, sample type and processing conditions.
How do I fit a pad to my plate?
To fit a self-adhesive backed pad onto a flat plate you should first of all remove the plate from the machine and place on a clear surface. Removal all trace of previous pad / adhesive and clean thoroughly. Peel back a small section of the paper that covers the adhesive and apply to the edge of the plate, careful to ensure that positioning is good. Ease off more of the backing paper whilst pushing the pad down onto the plate gradually, ensuring that no air pockets are allowed to form. Use a clean rolling pin / round bar to press the pad down onto the plate as you continue to ease off the backing paper until the whole pad is secured. Roll over the pad with the rolling pin to ensure it has been fixed well and check for any bumps. On soft cloths it is possible to pierce any small bumps that are found with a sharp knifeto allow the trapped air out, after which they can be rolled flat. A newly fitted pad should be conditioned thoroughly before use- harder pads can be conditioned with a diamond conditioner, softer pads with a conditioning ring. The polishing slurry should be dripped onto the pad during the conditioning.
What is lapping?
Lapping is a machining process where two surfaces are rubbed together with an abrasive in between, with the purpose of removing material in a controlled manner. Lapping typically produces a uniform surface that nevertheless is ‘damaged’ by the lapping process; the depth and nature of this damage will be the result of a combination of factors such as the particle size and material of the abrasive, the force applied, the material type, the lapping plate, and so on. Logitech can offer a variety of abrasives and lapping plates that will produce required results on various materials.
What type of lapping plate do I need?
Where a sample material’s hardness is measured at aproximately 4 Mohs or less, we would typically use a glass plate for lapping. Where the hardness is higher than 4 Mohs we would use a cast iron plate.
What is the standard groove depth of a glass plate?
The grooves on a Logitech glass plate are approximately 3mm deep.
How long will a glass plate last?
The lifespan of a Logitech glass plate is dependent on the usage and material being processed. Typically the plate should be replaced once the groove depth is below (1mm) 800 micron.
If it is a plain plate it should be replaced when the height from the process surface to the centre recess is below 1mm.
What is the standard groove depth of a cast iron plate?
The standard groove depth is approximately 3mm.
How long will a cast iron plate last?
The lifespan of a Logitech cast iron plate is dependent on the usage and material being processed. Typically the plate should be replaced once the groove depth is below (1mm) 800 micron.
If it is a plain plate it should be replaced when the height from the process surface to the centre recess is below 1mm.
Do you refurbish plates?
Logitech do not refurbish lapping plates due to the health and safety implications of handling and machining plates that have been used with various sample materials and consumables, some of which are hazardous to health.
What is the maximum sample load on a Logitech Jig?
The maximum load for samples used with a Logitech Precision Jig is:
PP5 used with angular adjustment plate – 2.8kg load
PP6 used with angular adjustment plate – 4.8kg load
PP8 – 6.7kg load
PP9 – 9.5kg load
What is the best parallelism for a jig?
Typical flatness of a sample lapped with a Logitech precision lapping jig is 1 micron per inch of sample diameter or better. If you are not achieving this level than we recommend that you check the condition and flatness of your lapping plate and jig.
What is the maximum angle on a jig?
The maximum angle on a Logitech jig is +/-3°.
How long will a Logitech Jig last?
If properly maintained a Logitech jig will last for many years with few parts needing replaced.
It is recommended that jigs are stripped down for maintenance at a minimum of every 6 months or when necessary?
