What Is A ‘Billet’ CNC Machined Part?

When you hear the words “Billet Aluminum” or “CNC Billet Machined”, what comes to mind? Usually people think of shiny and intricate parts. They can be ‘bling’ parts for automotive toys, such as snowmobile or ATV parts, or it can be something that is an upgrade from an oem part.

So, what is the difference between billet and… well, not billet? If it’s not a billet part, then it’s probably cast, which can also be machined afterwards. An example of a billet part would be something completely machined from a square piece of stock; no casting or forging involved. Billet does not only mean it’s made out of aluminum, although it is the most commonly known material for it. You can also make a billet steel, copper, stainless, or brass part.

Pros?

There are several advantages to making a billet part, both over cast as well as forged. The biggest advantage of machining is the accuracy and consistency. A CNC Milling center can hold much tighter tolerances than a mold or forging metal into a part. If you need a precise part, such as small gun pieces, CNC billet parts are the way to go.

Billet Aluminum Dirt Bike Engine Case
Billet Aluminum Dirt Bike Engine Case

However, it is depends on the company/machinist that is making the parts. If they are done right, all tolerances will be met, it will look “pretty”, and it can be just as strong, if not stronger, than a cast or forged piece.

Cons?

While it is easier to hold tighter tolerances, machining a billet part takes more time than casting or even forging a part. Once the mold is made, you can make parts in minutes, if not seconds! Set-up time is very costly, and setting up a CNC milling center or turning center can take hours. However, the more parts you run at a time, the more it will offset the set-up cost. That still doesn’t take away the cycle times and cost of tooling.

Compared to forged, it isn’t always as strong because the parts are literally ‘forged’ into place. However, you can take a forged part and machine extra features on it if you have a tight tolerance.

In the end, it comes down to what you need. Each kind of part has their own advantages. Billet pieces look really nice, can be made to hold precise dimensions, and as a result they may function better than a cast or forged piece.

Machine Shop Rates – What’s the Average Hourly Rate

If you want win in this competitive market, you have to be on top of your game by being efficient. Depending on what kind of jobs you’re running, you want to run the best equipment and tools for it, as well as utilizing them properly.

Fortunately, this doesn’t mean you need to buy the most expensive machine. As a general rule, the more complex the part, the more you’ll have to spend on precision equipment. On the flip side, you can charge more because it takes more time and money to run the job.

What Machines Are In The Shop?

There are a lot of factors that can determine the hourly rate of a shop. Shops that can utilize bigger are more powerful machines will generally charge more because the overhead costs are higher, and they can do more than just a small job shop with lesser machines.

What Kind of Shop Is It?

Comparing hourly rates of job shops and production shops can vary greatly. Running production is usually a larger shop with big machines that can run dozens or even hundreds of parts at a time. Efficiency is very important, and rates will often be higher. However, the orders can be started and finished in a fraction of time.

Smaller job shops that do more prototype parts and small batches are usually a little cheaper. However, the cost per part can be quite a bit higher because set-up time is expensive. The more parts you run, the lower the cost-per-part will be.

Quality or Quantity?

Just because a shop has bigger and more powerful CNC machines does not mean it is a better shop. A small 3 man shop can be head and shoulders above a 20,000 square foot machining shop as far as quality goes. In order to meet or exceed the customer’s request, there must be at least one machinist in the shop that knows how to do that. You can’t just make a program on a CAD/CAM system, load it onto the machine and expect everything to run perfectly. In fact, programming is sometimes one of the easiest part of machining.

The difficult part is making a fixture that properly holds the part, choosing the right tools for the part (size, length, material), as well as speeds and feeds that will be the most efficient (shorter cycle times are good, but if you’re burning through tools every few parts, you’re spending more on tools and down time because you have to stop running the machine and set a new one up; Time = Money). Some characteristics of a well rounded and skilled machinist can be found here.

Lets See Some Numbers!

Currie Engineering
Currie Engineering

So, you want to see some actual dollar amounts for machine shop rates… There’s a few different ranges of numbers, and as a general rule, you get what you pay for. $40-55/hour is considered cheap in the manufacturing industry, and while you may be able to find a local shop that has a rate that low, their work will probably reflect. However, if you need to make parts with wide open tolerances, you can save a lot of money going to a company that is 48 bucks an hour. Manual mills and lathes may be the majority of machines found in a shop like this.

60 to 80 dollars per hour is the average machine shop rate in most parts of the U.S.. Electricity is and overhead costs play an important role in what a shop is charging. However, the most important factor would be quality and type of shop. Prototype and short run parts are expensive due to set-up times. If you need to make a part with tight tolerances, that will greatly narrow the choices down. The shops that are able to make high precision and good looking parts know that, and are able to charge more because other shops can’t compete with their quality.

If you were wondering about the top dollar shops, there are some out there that charge $100/hour and beyond. Why? Along with the above mentioned, the high cost is because they are large shops with multi-million dollar machines that produce a high overhead to run, including well-experienced machinists that often get paid a better wage because of their expertise. It may seem ridiculous if you’re new to the career, but if you add up all of the expenses of machines operating, tools, inspection equipment, coolant and chemicals, electricity, and obviously the machinists/programmers themselves. After adding all those numbers up, they shouldn’t be more than what the company is making per hour, especially if the owner wants to make a profit.

In the end, it really depends on the kind of work that is being done. The higher precision and meticulous that stand strongly behind their quality will charge more, but if you have fussy parts, it is well worth the cost as opposed to rejecting the same part from a lesser shop that can’t meet the tolerances.

CNC Software For Machining – What Is The Best CAD/CAM System?

If you want to be a programmer or make your own parts some day, you’ll want to get a good software for CNC machining. There are a lot of different systems out there, but you don’t always need the biggest and baddest one if you can make your parts with a cheaper software.

CAD vs. CAM??

First of all, lets answer this question on CAD versus CAM systems. CAD programs are used mainly for making part drawings, blueprints, and make an overall model for the part you are going to machine. CAD is for generating toolpaths for the designed part. This is usually with G-codes and M-codes. Why do I need these, you ask? Well, to be honest, you don’t. You don’t even need any kind of software for machining. That is, unless, you don’t want to write everything by hand.

Lets face it, technology has skyrocketed in the past few decades, and even in the last 5-10 years, efficiency and quality are in high demand. China still can’t compete with USA made stuff, but for everyone to start buying from the United States again, companies want to buy parts and tools at a Chinese price tag. In order to bring the cost down, efficiency is extremely important, and this doesn’t just include programming a part (Read more about this on my Keys To Being A Good Machinist post).

Computer-Aided-Design

In order to be efficient, buying a CAM system may be necessary if you get a lot of blueprints and drawings. You will be able to make part drawings, fixtures, and jigs, which can also help reduce set-up times (the ultimate money maker/loser).

You can draw 3D models of parts to see different views of it, which can help the programmer when making toolpaths for it. With Cad software, you can put pieces together with an Assembly feature. With this, you can see what it looks like when the part is in the fixture you also designed. You’ll be able to determine what tools to use and how to optimize the set-up before you even start cutting metal.

There’s a lot of CAD systems out there for CNC machining, but if you’re running a real machine shop and need to be competitive, you’ll have to shell out some dough to get one. Free software will not get you very far, which is why it’s free. However, you may be able to get a free trial for paid software, which I recommend if you have the time. The most popular CAD systems include: Solidworks, AutoDesk Inventor, BobCAD,

Computer-Aided-Manufacturing

When used together, Cam and Cad software can be a powerful combo because they save time, which relates to money. If you have to hog out a billet part, writing out a program on the machine or by hand can take hours, and sometimes days if the part is large and/or complex. While I believe that you should be able to hand-write CNC programs first, CAM software can make almost any part in a fraction of time.

In the system itself, once you have the part model loaded, you don’t even have to write any kind of code; the computer does it for you! Let me explain… Lets say you have a 2 x 2″ square part that you want to mill down to a height of 1.5″. In the CAD program, you set the stock size and where the offsets will be (X, Y, Z zero). Once you have that, you pick the tool you want to use (we’ll just pick a 3″ face mill for this operation). Then you pick what kind of toolpath you want it to run; there’s a lot of options for this, but we’re just milling off the top. After that, it’s just setting your parameters for where you want the tool to start and end, how much material to take off, how much you want to take off each pass, and what you want it to do after the operation.

There are so many things you can do with a modern day CAM system that it can be rather intimidating to someone that hasn’t used one before. If you get a training book or have an experienced programmer teach you, starting out will make things a lot easier. The more time you get on the software, the more you’ll figure out what you can do with it, which will help reduce operation times, as well as being able to make more complex parts.

Mastercam is one of the most popular CAM systems because it is easy to use and is fairly versatile. Surfcam, BobCAD, EdgeCam, and RhinoCAM are also great software for machining. It also depends on what you’re machining as well. Are you just doing 2-axis milling? 5 axis? Turning on a lathe? Live tooling? Doing a little research will help you find out the advantages of each CNC software system.

When it comes down to it, it really depends on how comfortable and experienced you are at using a CAD/CAM system, as well as how complex your parts are going to be. If you’re just using a 2-3 axis vertical milling center or a CNC lathe, you will more than likely be able to do everything you want on them with a more inexpensive software. Finding one that is easy to use should be high on the list if you’re just starting out. However, this can be a compromise that will hold you back when you want to do more technical operations.