Just how to Improve CNC Machine Tool Accuracy

How To Improve CNC Machine Accuracy

Certainly one of the main tasks in machining is ensuring that the new CNC machine tool is accurate and precise. But how will you choose the proper tool for your factory, given the bewildering number of options, configurations, and prices available?

In this article, we will walk you through the step-by-step process needed to optimize your CNC machine's accuracy, repeatability, and tolerances once you purchase a fresh machine tool.

Time to Buy New CNC Machine Tool
Suppose that you've a fresh manufacturing opportunity or task available to you. You check the engineer's drawing to know what must be done, and start to plan the sequence and process to machine a particular part.Hit on CNC Machine Tool Accuracy Calculation  to explore more about our services and sites. Hope you ll like our more services.

You go during your existing machines, and check on the skill proficiency of your machine operators to see if they are able to fabricate this part.

Unfortunately, your overall CNC machine tools do not have the mandatory tolerances to make the part. They could be of a lower specification or are too old to cater to this new need.

When this occurs, you might wish to start purchasing a newer and more contemporary technology.

CNC Machine Tool Suppliers
A Tale of CNC Machine Tool Suppliers
At this point, you'll need to weigh the cost of manufacturing each part against the cost of acquiring new CNC machines.

You remember that which you used to invest for your overall machines, and set a budget that's as little as possible in order to maximise your profits.

10 years ago, you would've spent USD 80,000-100,000 for your Vertical Machining Centre. OK, you decide to set your allowance for a fresh CNC machine to be USD 75,000. Let's see what is available in the market.

Since the weeks pass, you contact various machine tool sales people. They attend for you eagerly, offering a range of CNC machines to match your set budget.

Some are lower in price. Others a little higher. Yet others may become more costly.

Most of the promises produced by these salespersons hinge on the actual fact their machines are newer and a lot better than your overall machines. However, none of those vendors consider the important points and tight tolerances of the machined part.

1 day however, a specific salesperson visits you. Once you informed him of your specific requirement—while showing him the drawing of your brand-new job—he takes a close look and studies it for a while.

Commenting that this kind of machined part may be “difficult to hold”, then suggested that you'd need machines with good tool holders and cutting tools.

He also highlighted that temperature control is key – specifically, the temperature of your workshop and overall machines. He further adds that the new CNC machine will require linear glass scales, laser measuring tools and a feeling probe to gauge the machined part and do auto-off-sets.

The salesperson explains that his CNC machine is preferable to your overall units and his competitors. Once you ask him for the estimated price, he quotes you – USD 150,000-200,000 – susceptible to your final specifications.

This is shockingly greater than your set budget! You might even suppose that owner was trying to fleece you.

However, additionally you start to think about what he explained, and realised that it made sense. All things considered, the other suppliers never mentioned these factors. They were only concerned with your axis XYZ, price and the available stocks of the machines, offering additional discounts if needed.

You contact another supplier of a trustworthy brand which is well known in the market.

During his visit he mentioned and repeated all of the points of the 2nd sales representative. He further explained that his machine tool uses the Linear Drive system which is considered the best in the market.

His CNC machine price? A shocking USD 280,000-310,000 – this is even higher compared to second vendor even though the machine size, spindle speed, and CNC controls are similar.

Now who should you imagine?

Understanding CNC Machining Standards and Accuracy
What we've just described happens each and every day around the world. There are numerous different categories, quality standards, and quantities of CNC machine tools – you need to know the differences in order to make the proper choice.

While machine tool vendors may promise tolerances of +/- 1.5 micron or less, remember that suppliers from different locations or countries may adopt different standards.

For instance, there is an impact between a JIS standard (used mainly by Japanese produced CNC machines) and a VDI standard (used by reputable European manufacturers in addition to employed by Hwacheon Machine Tool in South Korea).

These standards have already been used for over 30 years to measure and compare the accuracy quantities of machine tools, especially in Asia Pacific.

To know the differences – and the significance of these differences—it is necessary to learn and understand the method CNC machine tool manufacturer use when measuring their CNC machines after final assembly is done.

CNC Machine Tools Mother Machines
The Role of “Mother Machines” in CNC Machine Tools
All reputable machines tool manufacturer which provide high quality CNC machines utilize a “Mother Machine” to produce their own critical parts. They are machines which could achieve the highest tolerances – often within a few microns. The expenses of such machines in many cases are high, and may take the millions of dollars.

If a finish user receives a quotation / offer for a fundamental standard Vertical Machining Centre at USD 70,000-100,000 (X = 1000 with 10-12,000 rpm spindle), and a guarantee from the vendor that machine can achieve the exact same or even “on paper” better accuracy than a pricey “Mother Machine”, he must be extremely sceptical!

Such claims are too good to be true.

How Drive Systems, Guide Ways and Ball Screws affect Accuracy
How about linear drive systems? Are they really necessary?

Such systems were designed quite a while ago in order to help machine tools to reach faster speeds. Hwacheon Machine Tools had our own experience whenever we designed and built a Horizontal Machining Centre over 18 years ago.

Today, demand for linear drive systems remain present. However, standard CNC machines often omit such systems for their higher costs and greater complexity.

A linear drive system can enable you to achieve good tolerances and accuracy. However, modern machines with high quality Ball Screws and Linear Roller Guides – or Solid Box Guideways (hardened, grinded, and hand scraped to perfection) – can deliver better outcomes in long-term accuracy and stability.

Thus, a CNC machining centre with high quality ball screws in every axis in addition to solid hand scraped solid guide ways can achieve the exact same or similar accuracy to a linear drive version.