A few years ago at an audio show, I was talking with the President of a well-known, well respected audio component manufacturer. We were talking about how expensive it had become to buy the necessary parts that make up the average electronic device.
He pointed out a simple machined part on the front of a component that transitioned from each side of the front face plate to the metal box behind. That part cost $28.00. For two of them, $56.00 (left & right sides). For those two parts, and the flat faceplate itself, the total cost was just under $200.00. All so the customer could see something that looked nice and pretty - on a component retailing slightly less than $3000.00.
Most amps, preamps, DAC's and similar components are comprised of a variety of what manufacturing calls "component parts." These would include machined aluminum face plates, sheet metal bodies (or boxes), circuit boards, power supplies, capacitors, transformers and even mounting feet. Some manufacturers buy these components from outside sources. Some buy the equipment to make them in house.
Today, let's take a brief look at machining metal parts.
Simply put, machining is using a dedicated process to cut metal. In high end audio, one popular machined metal is aluminum. Most commonly, the nice shiny, sculptured, textured, gracefully flowing face plate on the front of your amp, preamp, DAC or other similar device has been machined by a machining center.
In the early days, machining was as much art as a process. Skilled machinists using vintage equipment made by companies like Davenport, Brown & Sharpe and Acme Gridley used their years of wisdom and experience to machine a part. Today, as complexity has increased, and tolerances have gotten tighter, industry inevitably moved to a more exacting type of metalworking process. Today we have CNC machining centers - CNC standing for "computer numerically controlled."
This process is used to take a block of aluminum, more popularly called a billet, and cut, grind, drill, tap, and machine a part into the final shape. If it sounds pretty simple, believe me, it really isn't. An operator is required to ensure the machine is functioning properly and a commanding knowledge of computers is needed to load the part drawing onto the CNC onboard diagnostics.
In a CNC machining center, the billet is fixed to a platform, or fixture, and the cutting tools will machine the part. Most will have what is called an auto tool changer so different types of cutting tools may be switched out automatically, not by hand. Once the part design has been loaded into the onboard computer, the operator presses start, and the machine essentially does the rest.
Once completed, the process is not yet over. Machining tends to leave sharp corners or create what are called "burrs." These can cut people's hands so sharp or protruding features must be ground down and removed. This is a secondary step typically accomplished by a "deburring process."
If any feature like some type of texture is applied, then that is, again, a separate operation. One machine used commonly in machine shops to apply a light texture is called a Timesavers machine. Each of these steps are an additional cost and added to the final purchase price of the part itself. If there will be any type of printing on the faceplate, that is also a separate step, and cost center.
Machining is the most expensive way to make a part. Why? Simple. It is because of scrap, process time and machine rates. Machining removes metal. Simple as that. All the metal removed is scrap. Most machining companies will accumulate that scrap and when there is enough, they will sell it to scrap buyers - for pennies on the dollar. Additionally, it may easily take a lot of time, compared to other processes, to actually do the machining, and time is money. And the hourly rate some shops charge for machining can be horrendous.
Let's suppose, and I'm picking costs out of thin air and not actual material costs, a company is going to make a faceplate for an amp. They want holes for shafts for control knobs, pilot lights, display screens and similar features. The back of the faceplate must be configured to attach to something - maybe a sheet metal box, or even more costly, a machined aluminum box. Oh, and don't forget the cost to machine the knobs and switches!
So, we'll start with our big chunk of aluminum, what we call a billet. Our billet weighs, let's say ten pounds. Our final part will weigh 7.5 pounds. That is a 25% scrap loss. If the billet costs $100.00 the part cost will include $25.00 worth of scrap. Put differently, the final cost of our nice, pretty faceplate will be based on the cost of the entire billet, or $100.00, not what the billet would cost IF the scrap cost was removed. Scrap is a very expensive part of machining. And again, I'm making these costs up for illustration's sake. They do not represent the actual cost of aluminum or scrap rates of machining a part. Sometimes, however, a 25% scrap rate would be great. I have seen parts with a 50% scrap rate.
We have not yet considered the cost of the machining process. Most machine shops apply to each machine a term called a "labor burden." This is the cost, per hour, to run that piece of equipment. This cost includes anything, building cost, utilities, operator salary, you name it. Each company will use their own formula to determine the labor burden. Once done, and this is overly simplistic, the material cost is multiplied by the labor burden and that determines the part cost. Any secondary process, like deburring or finishing, are additional costs and must be added as well. Only then can a final manufacturing cost be determined.
Machining is a very expensive process. It is perhaps best suited to high end audio because other processes require tooling of some type. Tooling usually means high volume, something audio is not. Tooling is very expensive. I once worked on a project for an automotive application where the die cast tooling costs alone were $350,000.00 - and that was an up front, one-time cost that had to be paid before the first part was produced. Normally, tooling costs are factored into part cost for a total price. That doesn't lend itself to low volume audio components.
However you look at it, machining is expensive. It raises the cost of the component above and beyond other production methods. Worse still, better pricing comes in two ways, faster production and / or higher volume. Typically, the machining process is neither and the resultant part cost is higher than other metal processes.
None of this, of course, addresses the profit any audio company adds to their total cost (manufacturing, packaging, marketing, etc.) to determine the final price for which a component will sell. That is a whole different matter entirely.
What is absolutely true, regardless of the component's final selling price, the cost to make it is likewise very expensive. So, the next time you see an amp or something else with a nice, pretty, sculptured, beautiful front faceplate, just remember, it is a machined part and was very expensive to manufacture.