Choosing the right materials is crucial for the success of your CNC machining project. Different materials, such as metals, plastics, or composites, each come with specific grades and compatibilities that affect machinability and durability. For instance, metals like aluminum and steel offer durability and are ideal for high-performance applications, while plastics such as ABS provide cost-effective options for less demanding parts. The material selection not only impacts the cost of the project but also determines the quality and performance of the final product. CNC machining materials used must align with your project requirements to ensure optimal results.
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Understanding your production volume needs can significantly influence the choice of CNC machining processes. High-volume production may necessitate the use of advanced CNC machines capable of handling large batch sizes efficiently, thereby reducing material costs and setup times. Conversely, smaller batch sizes may require machines that can be quickly adapted to new run settings, ensuring minimal downtime. It's essential to consider whether the CNC shop can scale its operations to accommodate increasing or fluctuating demand, ensuring a seamless transition between different project volumes while maintaining quality and efficiency.
The complexity of your designs heavily influences the capabilities required from CNC machining processes. Complex parts with intricate geometries may benefit from advanced CNC technologies, such as multi-axis machining, which provides high precision and reduces production time. Evaluating the design for potential simplifications can streamline the machining process, thus reducing costs and lead times. This includes considering design modifications that do not compromise the functionality but improve manufacturability, allowing for more efficient use of CNC resources and better alignment with project goals for complex CNC designs.
When choosing a CNC machine shop, determining their certifications is crucial. Industry-standard certifications like ISO assure quality management practices are in place, thus minimizing risks related to product quality and regulatory compliance. This certification is widely recognized and signifies that a shop adheres to stringent quality management systems, guaranteeing reliable and consistent results in machining projects. Additionally, other certifications may demonstrate specialization in particular processes, or technical expertise, such as AS for aerospace work or ITAR for export compliance. These certifications not only vouch for the shop's capabilities but also safeguard your project from potential compliance issues.
Understanding whether a CNC machine shop outsources parts of their machining processes is vital. Outsourcing can impact project timelines and the scope of quality assurance; hence, it’s important to identify which processes are outsourced. A robust network of reliable partners or suppliers is essential for handling outsourced jobs efficiently. However, outsourcing introduces risks that could affect the consistency of the output and overall project management. When evaluating a CNC shop, consider how outsourcing could influence the quality, cost, and delivery times of your project outcomes. Assessing their partnerships and management of outsourced processes will provide valuable insight into their capabilities and reliability.
To assess a CNC shop's capabilities fully, it's crucial to investigate their equipment and technologies. The variety of CNC machines like lathes, mills, or Electrical Discharge Machines (EDMs) shows their suitability for diverse tasks. Shops that employ updated technologies such as automation, advanced software, and IoT can significantly enhance machining precision and efficiency, allowing for more complex and precise outcomes. A diverse fleet of machines presents advantages in terms of capability and versatility, enabling the completion of various projects efficiently. Thus, understanding the equipment and technology at a CNC shop not only informs you about their current capabilities but also their future adaptability and potential efficiency in handling your projects.
Selecting the right material is crucial to optimize CNC machining outcomes. Common materials used include aluminum, steel, titanium, and various types of plastics. Aluminum is favored for its lightweight and excellent machinability. Steel, on the other hand, provides robust tensile strength, making it suitable for parts that demand durability and rigidity. Titanium offers a perfect balance of strength and weight, which makes it ideal for aerospace applications. Meanwhile, plastics like polypropylene and ABS are praised for their cost-effectiveness and versatility. Each material presents unique attributes such as thermal conductivity and corrosion resistance, which are critical when choosing the best material for specific applications in CNC machining.
The properties of materials significantly affect CNC machining outcomes. Material hardness and ductility directly influence tool wear and machining costs. For instance, harder materials can lead to rapid tool degradation, increasing costs. Further, these properties affect machining parameters like feed rate, cutting speed, and tooling choice. Evidence from multiple case studies shows that selecting appropriate material properties can enhance quality and efficiency. For example, using softer, ductile materials typically allows higher feed rates and increased cutting speeds, contributing to overall production efficiency. Therefore, understanding these material attributes is indispensable for achieving desired quality levels and cost-effectiveness in CNC machining operations.
Tolerances in CNC machining dictate the degree of permissible variation in a part’s dimensions and play a critical role in its fit and function within an assembly. High precision levels reduce the risk of part failure in applications requiring exact alignment and stability. CNC machines can achieve stringent tolerances as specified by industry standards such as ASME Y14.5. For instance, aerospace and medical device industries often demand tolerances within micrometers to ensure reliability and safety. For these sectors, meeting precise tolerances can be a matter of life or death, underscoring the importance of selecting CNC equipment capable of such exactitude.
In-process quality control is vital in maintaining consistency and minimizing defects in CNC machining. Common methods include Statistical Process Control (SPC) and real-time monitoring, enabling manufacturers to detect and correct variations during production. Applying Six Sigma principles further reduces defects, enhancing quality. A study from the Journal of Quality Technology highlights how these practices can cut operational costs by up to 30%. Effective quality control ensures high customer satisfaction, as consistent part quality is integral to end-users' trust and repeat business.
To maintain high precision in CNC machining, multiple techniques are employed. Advanced software like CAD/CAM systems enhance accuracy, while eco-friendly lubricants ensure smooth operations without component wear. Regular equipment calibration is crucial, as it aligns machinery to manufacturer specifications and maintains high precision levels. Testimonials from industry leaders like General Electric show that high-precision machining significantly improves production outcomes, meeting stringent industrial demands, particularly in sectors like defense and aerospace, where performance and reliability are paramount.
CNC machining costs are influenced by several key factors that need careful consideration. Material choice is a primary cost driver; exotic or harder materials usually cost more than common metals like aluminum. The complexity of designs also affects costs; intricate designs require more machine time and programming effort. Furthermore, machine time itself is a significant cost factor, as longer machining periods translate to higher expenses. In addition, the cost of labor and overhead can vary significantly based on the scale of the project and the location of the shop. For instance, a larger operation in a high-cost urban area might have higher overhead costs than a smaller shop in a rural setting. It's crucial to perform a clear and thorough cost assessment to prevent budget overruns. According to a study by the Association for Manufacturing Technology, 48% of companies face budget overruns due to miscalculated CNC machining costs.
Let's assume you have a working CNC machine that you've just acquired, but that you know very little about CNC. Let's further assume it is a mill and that you will be focused on cutting metal. You're ready to start milling custom chopper parts, build a tool changer, or scratch build a Colt handgun. With CNC, you can build almost anything and you're chomping at the bit to get started on your pet projects.
Not so fast! Remember, you just got the machine and you're a beginner. You're not ready for those projects yet.
If you have some idea how to make your first CNC parts, charge ahead with these 10 suggestions. Otherwise, you need to see the whole process of making a part mapped out in detail.
Take a break and go read our Beginner’s Step-By-Step Guide to Making CNC Parts. It will fill in those hazy details you’ve been wondering about, then, you’re ready for this article.
If you're even more of a beginner, and likely don't have a CNC machine yet, don't worry! Start with our "What is CNC?" article.
After that, here are 10 things you should focus on to maximize your chances of becoming quickly successful:
1. Buy Some Decent Cutters
Don't get the package of assorted sizes of cheezy imported cutters. You also don’t need the solid green unobtanium aerospace cutters from Men-In-Black-Cutter-Supply. Get some decent cutters from a reliable source that has reasonable prices. I like Lakeshore Carbide for example. Try for a name brand, one that’s on sale.
If you don't know what the good brands are, check out our End Mill survey. It'll show you which brands are most popular and have the highest customer satisfaction.
Having a decent quality cutter eliminates a whole bunch of problems right up front. I would also go with HSS when you’re just starting out. You’ll eventually want carbide for a lot of uses, but HSS is cheaper and more forgiving.
The exception is high speed spindles such as CNC Routers commonly have. They need carbide to stand up to the higher speeds.
Get yourself a few sizes:
Nothing smaller at this stage until you've learned on less delicate cutters. Buy 2 or 3 flutes for aluminum and some 4 flutes for everything else. I'd get 3 of each in each size to start. You are going to break some cutters, so get over it and accept the idea. It's a good thing at this stage to remind you to wear your safety glasses because you will break some cutters!
While you're at it, buy a full twist drill assortment. HSS from a decent brand on sale will work fine. I like the idea of replacing the ones I break with cobalt over time. That way my most-used sizes wind up higher quality. And one more twist drill tip-buy screw machine length, not the usual jobber length bits.
The screw machine length bits are more rigid and you will seldom drill super deep holes anyway.
2. Get a Decent Vise, a Clamping Kit, and a set of Parallels
Yeah, I know, vises are expensive, but workholding is very important.
Get a decent Kurt-style vise for your mill. It'll be money well spent on a valuable piece of tooling that will last for years. In my shop I have used Kurts purchased from eBay and a couple of brand spankin' new Glacern vises. There is sneaky stuff that goes on when you clamp a workpiece into the vise. If you don't have a good one, the workpiece will shift and you'll be wondering what happened.
You'll need a way to mount your vise to the T-slots of your table, so you may as well get a clamping kit too. Any old kit will do. Buy the one that is on sale at your favorite supplier. These are step clamp kits that give you a basic set of cnc clamps. There are many other types, and you can expand your collection as needed over time.
Lastly, you'll need a set of parallels, at least until you get proficient at making step jaws.
CNC Routers are a different story. You'll mostly be clamping things to your spoilboard. Do yourself a favor and go read up on how that's done so you can get a lot of good ideas before it's your turn to start clamping.
3. Get yourself a misting setup for coolant and use it while being paranoid about chip buildup
If your machine didn't come with flood coolant, and isn't set up for it (i.e. you don't have an enclosure to keep the wet inside), get yourself a misting setup. I got mine off eBay for about $100. It's a Noga. There are a lot of different brands. Get a jug of coolant to go with it. I use KoolMist, but again, there are a lot of brands.
Now train yourself to be paranoid about chip buildup.
Recutting chips is bad for cutters and in the worst case leads to breakage. Being paranoid means you're watching the cut like a hawk and you fiddle with your mister's nozzle until you figure out how to position it right the first time and every time thereafter to blow away the chips from the cut. Learn more about the different CNC Coolant options.
If you're a CNC Router user, the story is different, unless you plan to cut a lot of aluminum. If you're cutting aluminum, you still need a misting system. Otherwise, a ShopVac or even just blowing the chips out of the way with compressed air will serve as you cut wood or plastics.
4. Learn how to use MDI
Your next step is to learn to run your CNC as though it was a manual mill with power feeds and DRO's on every axis. In the process you'll learn some basic g-codes so that you have some idea what your program is doing the first time you run a real g-code program (that's a little ways away yet!). It's very convenient to be able to do this trick, and you can learn all about it through our article on this topic:
Don't stop there. When you've got a grip on MDI, start on the CNCCookbook G-Code Tutorial.
Start out with the cutter way high and don't try make any moves in the Z-axis so you won't crash the cutter into anything. Practice making moves in X and Y. Until the cutter goes where you want it to and you're not making mistakes.
One more trick: don't use G00 in MDI-that makes the machine move in rapids mode which is as fast as it can go. Use G01 and set a slow feedrate. "G01 F20" will make the machine move at 20 inches per minute (or metric units if you're in metric). You'll have a lot more time to react this way if it starts heading into trouble. Visualize pressing the red E-Stop many times so it'll be almost automatic when you need it.
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5. Get yourself a feeds and speeds calculator and use it
You're getting close to making your first cuts.
Do yourself a favor and get a feeds and speeds calculator. Trying to figure out feeds and speeds as a beginner or asking people on forums is a recipe for frustration and faillure. And it is such a false economy to try to save a few bucks by skipping the calculator or using a cheezy free online calculator. Stuff will go wrong that you're just not equipped to understand. So, get a decent feeds and speeds calculator so your spindle speeds and feedrate are perfect for that first cut.
We recommend our own CNCCookbook G-Wizard feeds and speeds calculator (natch!). It doesn't cost much more than 1 single cutter to get started, and you can use it for 30-days completely free.
Best of all, there's a great deal just for beginners and hobbyists that we call "G-Wizard Lite":
When you subscribe for 1 year of G-Wizard, you get Lifetime use of the product for up to 1 horsepower. You can do a lot with 1 HP, especially if you're a student or hobbyist. In fact, it may be all the power you ever need!
So check it out, your cutters will thank you and your projects will go by faster and easier.
6. Get yourself a Z-height measuring gizmo and learn to use it to touch off your tool lengths. While you're at it, get an Edge Finder and use it to touch off your Part Zeros.
Your machine needs to know where the tip of the tool is or terrible things can happen.
As a beginner, you tell it by using a Z-height measuring gizmo of some kind. Have a look at our article on the subject to see what's available. Don't get wrapped up in the fancier stuff in that article. The first few options will get your going.
Learn how to use these to tell the machine what your tool length is. This process tells your machine where the tip is in Z. To establish the position of X and Y you'll need and Edge Finder. The first thing you'll do after sticking a piece of material in your vise and inserting a tool in the spindle is to set these zeros.
You can learn more about touching off and setting part zero from our G-Code Tutorial.
Also take a look at our 2-part series on Tool Data Management for information on Z-Height Gizmos (more properly called touch setters) and tool lengths. Use your newfound MDI skills from #4 to start using your Edge Finder and Z-Height Touch Setter.
7. Learn to Tram your Mill and Vise
How to square and tram your vise on your CNC mill...
Tramming is what machinists call getting things square by sweeping an indicator around. It's a basic skill everyone needs to learn.
When you first start machining, get into the habit of checking your mill's tram every time you walk out into the shop. You'll know later on whether you need to do it every time, but for now, you could use the practice. While you're at it, be sure you know how to tram your vise so the jaws are aligned properly with one axis or the other. Let's don't try to square you mill just yet, but tramming the mill and vise are a good step at this stage.
For details on how to do this, refer to our Mill Tips and Techniques page.
8. Start out with wood, aluminum, brass, and plastic. Avoid stainless.
Okay, the very next step involves making some cuts. Sorry if it seems like you had to do a lot before getting there, but I did say I wanted to tell you some things that will help you succeed and there's quite a few things in that category!
One more is to avoid difficult materials for your first cuts. Stick with aluminum, brass, or non-metals like plastics and wood.
BTW, nothing wrong with sticking a piece of 2×4 in the machine to learn on, even if the eventual part is going to be made of metal. I often use wood to prototype what I'm doing until I get everything right. It's a lot cheaper than metal!
When you're doing okay with softer materials, graduate to mild steel. Only after you feel like you've pretty well mastered cuts in these materials can you try tougher materials. Master means you're not breaking or wearing cutters out too quickly, and your surface finishes no longer look like the material was attacked by a pack of rabies-infected beavers.
One more thing. It'll be tempting to try some "mystery metal." This is metal you think you know what is, that you got essentially for free, and that is therefore expendable. Trouble is, a lot of mystery metal is hard to cut. It's nasty cheap stuff that will break cutters and generally confound you. Not worth it!
9. For your first project, learn how to square a block of material and make yourself a few sets of step jaws in aluminum
Let's quit procrastinating and make some chips!
For this step, you're going to start by learning how to square a block of material. Get your saw and cut out some pieces of material that are slightly oversized to serve as vise jaws. Google "Kurt Vise Jaw Dimensions" to find drawings of jaws if you need some. As mentioned, cut the stock slightly oversized from aluminum. Now you need to square those blocks. Squaring means you will make a series of milling cuts until all sides are properly parallel or perpendicular to one another, at which point the workpiece is "square".
The proper steps for squaring a block of material are described on my Turner's Cube page. The recipe described there is one I got from the great book, "Machine Shop Trade Secrets." Pick up a copy to continue your learning process.
One thing about the Turner's Cube material squaring: I use a Face Mill, but you should start out doing it with multiple passes and a 1/2" endmill. Why? Because Face Mills generate a lot of force. You can stall the spindle, yank the work out of the vise and throw it across the room, and other shenanigans a beginner could do without.
Leave the face mill in a drawer if you have one already and do it with a 1/2" endmill the first time until you know a little more what you're doing. Same goes for fly cutters, and for the CNC Router crowd, those big cutters you use to surface spoilboards. You're not ready for them yet.
Having squared the material, your next task is to cut it to size by continuing to mill it until it is a perfect fit for your vise jaws (you'll need 2 square pieces, one for each jaw). The last step is to drill and countersink the mounting holes.
Actually, I wasn't completely truthful. Once you have mounting holes, the last step is to mill a step along each jaw, maybe 1/8" square. Now you can use that step instead of parallels when you drop material into the vise. Over time, you'll learn a lot more tricks with aluminum jaws, but remember: it all started here with your first set.
10. Graduate to CAD/CAM
Friend, you're now able to do the basics. Sure, there's a lot more learning to do, but you're in a position to have a leg up on the manual machinist down the street who has a Bridgeport and no CNC. Your next step is to start pumping out the g-code. To do that, you'll need to be proficient with CAD/CAM. This is going to be your biggest step yet. Neither CAD nor CAM is very easy to learn.
I give myself 2 weeks to feel comfortable with a new program, and I've had the luxury of learning quite a few so far. If this is your first time, get ready to drink from the firehose.
I have put together a bunch of pointers to make it as easy as possible for you to choose the best CAD CAM software for your needs. Check out our Best CADCAM Software for Beginners article. It is chock full of buying guides, evaluation tips, how to learn ideas, and best of all, it has a guide to the secret deals on the most popular packages that can save you money. These are deals most people have no idea exist, including one from CNCCookbook.
Bonus: Delay the need for CAD/CAM a little while with Conversational CNC
Many talented manual machinists run afoul of CADCAM and it stalls their ability to be productive on CNC machines quickly. Even after they've learned CADCAM, they're still left with the feeling that manual machining can make simple parts faster than CNC, because they don't have to stop to make a CAD drawing and run it through the CAM package to get g-code.
Instead, they can just make a simple bracket with 4 holes shooting from the hip.
Conversational CNC makes it possible to do that with a CNC machine. Imagine changing the long essay test that is CADCAM to a quick multiple-choice quiz. That's what Conversational CNC is all about. Here's the pictorial menu of Conversational CNC operations that can be performed on a mill:
You pick the operation, a popup asks a few simple questions, you press the Insert button, and you've got your g-code. We've built Conversational CNC right into our G-Wizard Editor product so you won't have to purchase an expensive stand alone Conversational package.
You'll still need to learn CADCAM, but with Conversational CNC you can be making simple parts before finishing the CADCAM learning curve.
Congratulations, you've got some Basic CNC Skills!
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