To continue on a previous post regarding machine maintenance, I will answer the second question…
What is the best method of measuring platen squareness?
The most common method is to use a set of inside micrometers to measure the distance between the platens. Before you do this, you should first remove the mold, clean the platens, and use a straight edge to determine corresponding areas on the stationary and movable platen which are flat. Next, install a mold which covers at least 2/3 of the distance of the tie bars. Lastly, measure the parallelism of the platens (at each corner) when the mold is opened, closed, and under full tonnage. This will provide you with a great detail of information regarding the parallelism of the platens, the linearity of platen movement, and possible tie bar stretch.
The best method of measuring the parallelism is to use a laser system. These systems use a laser mounted perpendicular to the movable platen and a detector on the stationary platen. These systems are connected to a computer which will collect data and analyse the parallelism and linearity of movement during mold closing, and clamping. This data will give you great specific information regarding parallelism, angles, twist, and movement.