Investment Casting Morning

Wednesday I blew off all the work I have piling up and zoomed up to Hsinchu to watch an investment casting facility that makes parts for my friend Michael Klein pour aluminum. Our journey began and ended in the grimy factory town of Hukuo, full of Thai and Filipino restaurants catering to the local foreign laborers, where Michael makes his home.

Breakfast

A large temple offers a promising excursion on a later date.

A religious procession, all-male, passes by.

Passing through some of that good Taiwan farmland...

Testing the super macro on a hibiscus.

The factory

At the factory.

Investment casting is also known as the Lost Wax process, because the wax is burned away in the creation of the mold, leaving the mold behind (you'll see). The casting process begins with the molding of a wax replica of the part to be molded. Here the worker, moving rapidly, extracts the wax replicas from a mold.

Here are the parts. They will be fixed to a tree, 9 parts on each side, 18 to a tree. Ok, it's gibberish now, but it will make sense in a few minutes.

Inspecting parts for motorcycles. This factory is actually quite well known in the business, and manufactures parts for a number of famous overseas brands.

After being attached to the trees, the wax replicas are taken to this room to be coated with sand in two steps. First, they are coated with an extremely fine, hard sand that has a very high resolution and reproduces the part with extreme precision, and then they are coated with a coarser sand.

Here a worker coats one of the parts.

Checking to make sure everything is OK. Note that there are nine parts on a side.

A close up of a part, in this case, a heat sink.

Coated and dried, these parts await molding.

Parts coated with the fine sand. The part here are three pipes, the other pronglike portions are actually part of the mold, not the part. They will become tubes when the mold is made, enabling metal to flow to the part.

Molding a plate. The tiny stubs are actually to permit the wax to flow out when it is melted.

After the wax replicas have been coated with sand, the next major step is to place them in a furnace.....

...where the wax is melted away, leaving the sand behind....

....in the shape of the mold and the parts to be molded. Here Michael hefts one of the molds after the wax has been "lost" -- melted away. Note the smooth interior. The cup here is not part of the molded part, but is only part of the mold into which the molten metal is poured. Michael said that they recover about 95% of melted wax for reuse.

Here a pile of aluminum cups waits to be melted down and reused. The molded parts have been removed, processed, and shipped to the buyer.

Globalization: aluminum ingots from Dubai, to be processed into parts in Taiwan, for shipment to the US for assembly into a final product.

The aluminum furnace.

Here the molds await heating so that the melt can be poured into them.

The worker blows the inside of the mold clean before pouring the aluminum.

Touching up the mold before pouring begins.

Critter break: we went out to wait for the pouring to begin, and I shot a few critters.

I was quite taken with this colorful fellow, whom I had never met before.

Back inside to watch the workmen pouring the aluminum.

The worker dipped the bucket into the furnace, took out some liquid aluminum, then poured it carefully into the cup, where it ran down the tree and through the gates into the nine parts waiting to be molded. The heat emanating from the molds is incredible, and Michael and I went out in the sun once in a while to cool off.

The second cup there is called the riser. It acts as a reservoir to insure a constant and stable flow of metal into the molded parts.

The molds are preheated in a furnace (can't pour molten metal into a cold mold!). Here two workers wait while the dipper is at work.

A mold is removed from the furnace.....

...and placed on the floor, ready to be filled.

A production run.

Freshly poured metal.

The workman chipped away the sand to have a look at the part.

The metal and the sand mold cool at different speeds, resulting in the mold cracking. That's a desired effect, it doesn't bother the part -- since the mold will have to be removed anyway. Often, Michael explained, the part unmolds itself as the mold shatters from differential cooling.

A worker stacks the molds.

Removing the mold to have a look at the part.

Another run of molds readying for action.

You're not needed! Investment casting reduces machining after the part is made.

After watching the aluminum being poured, we headed out to a local temple to enjoy the views. Here tea awaits plucking, processing, and export.

The temple.

Enjoying the view.

Enjoying the same view using my 48x digital telephoto. Eat your heart out.

[Taiwan]