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Posts Tagged ‘Cast Iron Plate’

Large Gray Iron Plates for Workholding Made in China

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 moulding 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. 

For more information about gray iron plates, please check Dandong Foundry’s Blog.

For more information about our company, please check Dandong Foundry.

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Plumbing Tips – Inspection

It is clearly important to be able to gain access to all parts of the underground drains. This is usually done by providing inspection chambers at various points. To meet the Building Regulations, cham¬bers have to be provided: at junctions between drains; where the drain changes direction or gradient; at or near the beginning of the drain; and at intervals of not more than 45m on long, straight runs. In between the inspection cham¬bers, the drains should be laid in straight lines.

The usual form of an inspection cham¬ber has sides made of brick, often cement-rendered either on the inside or the out¬side. At the base of the hole are open channels to which the drains are connec¬ted and along which the water in the drains runs.

The inspection chamber is at a junction between three drains. The branch drain is connected to the main one with a specially shaped half-channel bend which is swept in the direction of the flow of water through the main channel.

The channels are built up with benching – smoothly finished concrete shaped to direct any splashes back into the chan¬nels. The top of an inspection chamber is covered with a manhole cover a heavy, cast-iron plate set in a cast-iron frame. If there is a manhole cover within a building it usually has to be screwed down to the frame and the joint sealed with grease.

With modern drain materials, it may not be necessary to have full-scale inspec¬tion chambers at all junctions and bends in the drain. Instead, rodding points may be used. Small circular inspection cham¬bers may also be fitted.

A rodding point has a length of pipe with a gentle bend connected at an angle to the drain. The other end of the pipe leads to ground level and is covered with a suitable removable cover. If the drain needs unblocking, the cover is removed and drain rods passed down into the drain. Rodding points are small and neat – unlike large, ugly manhole covers – but some inspection chambers may still be needed.

In older properties, the inspection chamber at the boundary of the property may have an interceptor trap fitted at the outlet of the channel. To gain access to the length of drain between the trap and the main sewer, the trap has its own rod¬ding arm which bypasses the U-bend. The rodding arm is fitted with a stopper (sometimes secured with a chain) to prevent the drain water from bypassing the U-bend, too.

This inspection chamber may also be ventilated by means of a short pipe pro¬jecting above ground from the side of the chamber. The pipe is usually fitted with a grilled ventilator, behind which is a flap. The theory is that the flap allows fresh air into the drain but prevents foul air from escaping. Ventilators are probably more of a hindrance than a help, and damaged ones can be removed completely rather than repaired. Interceptor traps also give problems the rodding arm stopper can fall out and cause a blockage in the trap if it is not suspended by a chain.