Large Gray Iron
Plates for Workholding
Made by Dandong Foundry
We made these large plates for our client in USA.
Their material is Gray Iron Class 35, with Brinell
hardness BH 160-220. Their weights are from 60kg to
300kg per piece. Two front and back surfaces need to
be grinded to Rz3.2. This is very smooth as mirror.
There is no any sand holes or air holes on any
surfaces or inside. This requirement is very high.
These plates must be stress released by electric
oven/furnace. Otherwise, the inside stress will
cause the tiny deformation in the future. During
machining, you have to machine them step by step. If
you machine too much allowance in one time, the
machining will cause the deformation, and this plate
will be failed. Moreover, you have to find a large
surface-grinding machine / flat grinder to grind it
by one time.
As for the casting process, the resin sand molding
process will be necessary since the resin sand
moulding can effectively prevent the deformation
during cooling period.
Our iron foundry has produced these plates for over
two years. Actually, we have not made them very well
yet. We have not reduced the defective rates to low
yet. This is also because of the typical shortcoming
for sand castings. You never can prevent the air
holes, sand holes and small shrinkage. We have
bought a portable X-ray detector to check the inside
shrinkage and sand holes, but we can not completely
prevent the inside flaws.