When you’re finishing a CNC machining project, sometimes you’ll have to find a way to make an already existing hole slightly bigger. This is when you’ll want to use CNC reaming. It can help you refine a pre-drilled hole to a specific size and give it a smooth finish. This technique is commonly used in the manufacturing sector to create parts requiring high accuracy.
Let’s clarify what CNC reaming is, what you can achieve with it, and how it can improve the final finish of your CN projects. It should help you understand the CNC reaming process and how it enables you to make precise and high-quality components.
The Basics of CNC Reaming
CNC reaming is a finishing operation done with a multi-edge tool that gives the holes of your workpiece the desired finish and precise diameter. It helps you refine the hole size with great accuracy. Your projects may require specific hole diameters, which you can achieve through reaming.
In many industries like automotive, aerospace, and electronics, even the slightest deviation from the required dimensions can lead to the failure of an entire system. Reaming plays a significant role in achieving this precision. Suppose you’re working on a piece that needs a hole with a specific diameter. A reaming tool allows you to ream a hole to an accuracy of up to 0.01mm, which is incredible when working on tasks requiring high precision.
Why is Reaming Used in CNC Machining
It is to achieve a precise hole size and a better surface finish on the final product. It gives the drilled holes a more accurate dimension, improved surface roughness, and better alignment.
One of the significant benefits of reaming in CNC machining is the ability to achieve precision holes. That is particularly beneficial when the hole is used for alignment or fitting parts together. For instance, precision holes created through reaming are invaluable in assemblies where parts need to be aligned perfectly.
Another benefit is the improvement of the surface finish. It improves the part’s appearance and performance by reducing friction, leading to its longer lifespan, less maintenance, and better functionality.
How to Use a Reamer in CNC Machining
A reamer is a rotary cutting tool that you’ll use predominantly to finish or widen holes. It has a cutting edge that gives your workpiece a precise finish. Now, let’s break down how you can use a reamer effectively.
- Turn off the CNC machine before installing the reamer to avoid accidental cuts or injuries. Mount the reamer into the machine’s tool holder and fasten it securely.
- Set your CNC machine to the appropriate feed rates. That is the speed at which the reamer moves into or along the workpiece. Reaming differs from CNC drilling and cuts slower due to its different design and function. It will prolong the reamer’s tool life.
- Start the CNC machine and let the reamer do its job. As the tool moves along the workpiece, it will cut and finish the hole to your desired diameter and smoothness.
- After the reaming process, turn off the machine and carefully remove the reamer from the tool holder. Clean it thoroughly before storing it away. That helps maintain the cutting edge of your tool, ensuring it stays sharp and ready for future jobs.
Types of CNC Reamers
There are many types of reamers you can use during CNC machining, and the most common types include:
- Chucking reamer – Designed to make pre-existing holes more accurate, ensuring a perfect fit for any inserted parts.
- Shell reamers – Ideal for enlarging or finishing a hole, typically used with a shell reamer arbor for stability.
- Taper reamers – Used to create a tapered hole, often for pins or threaded inserts.
- Ball reamers – Designed to create ball-shaped holes and commonly used in the automotive industry.
- Line reamers – Used to make long, straight holes for pipes or tubing applications.
- Adjustable reamers – They offer versatility with their adjustable blades, allowing for a range of hole sizes.
How to Calculate the Ream Hole Size
Know the size of the hole you want to create so you can calculate the ream hole size. Say you’re aiming for a 1-inch hole. Start by drilling a hole slightly smaller than this, around 0.75 inches. Then, use a reamer to enlarge the hole to the desired size. If your drilled hole is too small, you might exert too much pressure on the reamer, causing it to break. If the hole is too large, the reamer won’t have enough material to work with, and you won’t get the right size.
The Difference Between CNC Reaming and Boring
CNC reaming and boring refine holes in a workpiece but have distinct differences. CNC boring uses a single-point cutting tool mounted on a boring bar to enlarge a hole made by previous processes. Reaming uses a multi-point cutting tool to improve the hole’s diameter and finish accuracy.
To help you visualize these differences, let’s look at a table comparing CNC reaming vs boring.
| Feature | CNC Reaming | CNC Boring |
| Purpose | Finishing pre-existing holes | Enlarging holes, creating new holes, facing/grooving surfaces |
| Speeds and feeds | Relatively high speeds, moderate feeds | Variable depending on operation and material, generally slower speeds and heavier feeds than reaming |
| Surface finish | Smooth | Good, but requires additional finishing depending on the application |
| Applications | Tight-tolerance holes, critical components | General machining, larger holes, moderate tolerances |
The Final Touch
The CNC reaming process can refine pre-drilled holes, ensuring a precise and smooth finish. It gives machining unmatched accuracy and perfects the size and finish of pre-drilled holes. It’s not a standalone operation but a finishing touch after drilling or boring.
Next time you see a perfectly finished hole, remember the invaluable role of CNC reaming in achieving such precision.
FAQs
1. What is the main role of a reamer in the CNC machining process?
A reamer in CNC machining refines existing holes and improves their accuracy, finish, and diameter. It ensures precision and smoothness, delivering high-quality holes that meet exact specifications.
2. Do I have to use a reamer in CNC machining?
It isn’t necessary but is beneficial and essential for creating accurate, smooth holes. It’s not needed for rough machining or less precision-demanding tasks.
3. What are some common problems that I might encounter during reaming?
You may face hole size and straightness errors, poor surface finish, and rapid tool wear. These issues often result from incorrect reaming speeds, improper feed rates, inadequate lubrication, or using worn or damaged reamers.