CNC (Computer Numerical Control) machines use various types of guideways. These nodes are used to perform a specific range of tasks:

Move moving machine parts along a given path.
Carry loads while working.
Being a support for machine parts.
It is important that the movement along the guideway must have the necessary precision and minimal friction. In this article we will discuss which guides meet the requirements and are the best in terms of price/performance ratio.

Polished shafts
Polished shafts round shafts are an affordable and popular solution. They are made of durable high-alloy steel and are usually of the ball bearing type (e.g. ШХ-15). Polished shafts are easy to fit and machine, and are inductively heated and ground during the production process to prolong service life. The polished top layer provides low friction. Fixing and mounting is done manually – from both ends of the shaft. However, despite all the obvious advantages of a round shaft, it has many disadvantages:

The frame has no fixings. The shaft is mounted with two fasteners at each end, which increases the degree of error during machining.
Over time, the shaft may bend and sag due to the lack of fixation on the base. This makes it impossible to use polishing shafts longer than 1 meter.
Polishing shafts are easy to design and can be handmade from low quality non-hard metals. We recommend purchasing products from major suppliers.

Polishing shafts on supports (cylindrical guides)
Cylindrical guideways This type of shaft has a support – a cylindrical guideway that provides support for the entire working area of the machine. This reduces the possibility of long sections sagging under weight.

The support shaft is attached to the machine base through a threaded hole. Like polishing shafts, cylindrical shafts have the same drawbacks – fragility and high bushing clearance.

However, the advantages of the tool compensate for these drawbacks – higher load capacity due to the absence of sagging along the length. It is worth noting that accuracy may be reduced when using support shafts on smaller machines with heavy-duty skids. The quality of cylindrical shafts varies considerably, depending on the specific manufacturer.

Profile guides
Profile guidesProfile guides are divided into two main types: ball guides and roller guides. Unlike the previous example, profile guides improve accuracy. They are attached directly to the frame and therefore have a long service life, a high level of load capacity and wear resistance, and little or no clearance (between surfaces).

The contour guides ensure even load distribution along the length, ensuring high accuracy and straightness even when moving heavy duty carriages. Installed on machines for milling metals (steel, cast iron), stone, etc.

Defects:

Mounting to machines is difficult.
Fastening points must have low roughness and high straightness.
The production of contour guides is complex and expensive, which is why they are practically not manufactured in the country. Therefore, most of the products on the market are of high quality.

To summarize:
If you plan to use a machine with a working length of more than one meter or want to mill hard metals, then you should use contour guides.
If you want to use a machine with a working area of less than one meter for soft materials, then cylindrical guides and polishing axes are for you.
That’s all for today. We hope this material has helped you to select the right components for your machine. If you have questions about this topic, please contact us in any way that is convenient for you. We’ll be happy to answer.