CNC Machining’s Best Kept Secret: Parametric Programming

Even experienced CNC machinists aren’t always familiar with parametric programming. And those that do know of it, often don’t know how to use it. Once you understand what it is and how it can improve your CNC machining life, you’ll wonder why you hadn’t taken the time to learn it in the past.

What Is Parametric Programming?

You can easily compare this type of programming to any computer program language. Parametric programming allows you to create custom macros, which as you might guess, are quite useful to many businesses. But as it stands, they’re not even using the custom macros which could boost their productivity noticeably.

Here’s some other situations where parametric programming comes in handy:

 Families of parts: 

Pretty easy one here. If you cut families of parts repeatedly, you’re going to benefit from custom macros.

General purpose routines: 

Okay, so let’s say you’ve created custom macros for parts families. Well, you do likely also have certain cuts you have to make on a routine basis. You know what they are. And they’re a perfect opportunity for parametric programming.

One benefit for this kind of parametric programming is that programs become shorter and easier to change. If you’d like to learn more, these routines are commonly referred to as “user-created canned cycles.”

Any complex motion you need to make: 

Let’s say you need to cut a taper on a thread. Now, that’s a difficult motion to pull off. Instead of programming that one every time, create a macro to save yourself time. To put it in perspective, parametric programming would only require 50 lines or so of code in G code. Do this on a CAM system, and the exact same process requires hundreds or thousands of commands.

 Any other process that takes time: 

Think about how you use your CNC machinery here. How long does it take you to set it up? What if you need to transfer a program? Consider all the steps you have to implement with your CNC machine, and then replace those repetitive ones with macros.

When it comes to parametric programming, the most common uses you’ll find for it include for families of parts and creating your own canned cycles. Once you get these functions programmed in, you’ll be glad you did because it saves you so much time and improves your productivity. 

Everything You Need to Know to Get Started with Ballscrews

New to CNC machining? You might wonder, like many others, what ballscrews are all about.

What is a ballscrew, and why would you use one anyway?

First, take a look at ballscrew theory. Think of this as your introductory college course to ballscrews. Very simply, ball screws transfer rotational motion into linear motion with next to no friction. They do this at about 90% efficiency. This is far more efficient than any other method that does the same. This greater efficiency also means ballscrews also have a much longer life than other components that perform the same function.

Why would you use a ballscrew?

They’re usually used in situations where you have a lot of lead or need a lot of life. They compare to lead screws, which get used for the same purpose, but they’re used in smaller, lighter duty applications. Lead screws also have more customizability, as you can change the leads, sizes, and their nut configurations quickly and with ease.

How do Ballscrews Work?

They’re pretty simple in nature. The threads on a ballscrew allow a hardened steel ball to transfer rotational motion from a ball nut into linear motion along the shaft. Inside of the ball nut, there’s grooves, and these grooves fit with those on the shaft, allowing the multiple balls to travel along.

Ballscrews also have a high degree of accuracy. They can easily be accurate to 1/10000^th of an inch.

Comparing 2 Types of Ballscrews

When you look to buy ballscrews, you’ll run into these common types:

Ground ballscrews

Rolled ballscrews

Ground ballscrews are made when abrasive wheels cut the channels the ball moves through. While they carry a higher price, they do have high tolerances and exceptional accuracy. They also tend to operate much more quietly than rolled ballscrews.

Speaking of rolled ballscrews, their main benefit over ground ballscrews is their cheaper cost. In fact, they can easily cost 15-20x less than their ground counterparts. However, you will sacrifice accuracy. Rolled ballscrews can be found with accuracies similar to that of ground ones. But, they also then carry the same price.

In nearly every case, ground ballscrews work out better than rolled. So when deciding which to use for your CNC machine, the question usually comes down to the accuracy you need and the price you’re willing to pay for it.

Hope that helps!