Monthly Archives: June 2011

About a dry clutch of SR400, I went to a casting shop.

Almost, I could design the dry clutch.However, a case is a problem.
The trial product hollow out a genuine cover.Then make a bowl with aluminum and weld it.
But how about mass-producing this method?
If I buy a clutch cover with genuine parts, it is over 20,000 yen.The price of the kit will be very high.
The shape of the genuine case is such a feeling this.

When I shaving it and make it, t=40 is necessary for the material even at least.And a lot of chips comes out.

So I took an appointment to a nearby foundry and visited.

Because it is a small lot I thought about going forward with a sand mold.
Although the president met for the first time, he took time and gave a detailed explanation.
This is the information on sand mold casting obtained there.

Even if you look at only this, it seems to be told that “Oh sand mold, I know that”, but seeing is believing.
I was able to actually show the process.So, I understood many things I do not know without looking.

It is such a feeling when I chase a process in detail.

1,Attach formwork and “the stick of a tree becoming the exit of hot water” to wood mold.The upper and lower formwork and wood mold restraints are pins.This pin and wood mold, clearance of the hole of the formwork are approximately 0.5mm.Conversely, there is a possibility that the upper mold and the lower mold are displaced by that amount.Formwork is standard.Select the size according to the product size.Naturally, it is necessary to decide the formwork size before the wood mold production.
The exit of the hot water is common to all wood mold.

2,Place formwork + wood mold on press machine.

3,Stuff sand and press.

4,Turn over and do the same for the lower mold side.

5,Give vibration in a vibrator and pull a wood mold out of a sand mold.

6,To cast in a mold.

Draft angle is necessary to remove wood mold from sand mold.It is necessary more than 3 degrees.

In terms of cost, in the case of a small amount, the wood mold production cost is the majority.Even simple things 300,000 ~.
The cost of casting is several thousand yen against one product even if it is estimated high.
Materials of the wood mold is “real tree” or “chemical wood”, the material is not expensive.
In the past, some people said they wanted me to make parts for cars and motorcycles.However, the president said they frown at the price of wood mold .
For reference, the president said that it would cost 8 billion yen if all of  Daihatsu Mira was made with one item.

I was surprised.For products with production number exceeding 500 pieces per lot, it is done with die casting.
From such a small amount! ? I thought.However, using pre-hardened steel or FDAC seems to last around 1500 shots without quenching.It’s a way to make cheap molds for small lots.
The major manufacturer seems to use the mold of FDAC from the prototype to the initial lot.And it seem to use the quenching mold of SKD61 after the second mold properly.
But it will be hard because it is HRC 38 – 42.
Certainly, there is a difference between making wooden molds and making molds are reversed, but both are designed.The time and labor of the program are the same, so it is faster to produce the mold and the product is stronger.

Compared with wooden molds, the castings (die-casting products) made with molds have a chill layer on the surface so they are stronger and the accuracy is better so we can make the thickness thinner.
Good thing all it is.

The point is that if we could even make wood mold in my company, I could compress the initial investment.
Let’s try it .