Wonder why CNC machine tools with similar specifications are priced so differently when comparing catalogues and quotations? Do higher purchase prices mean better quality, performance and durability for your CNC machines?

Did you experienced that your newly purchased CNC machines perform not only better than your previously purchased machines but your cutting tools also last longer? Is the newer CNC control so much more advanced than the previous version? Or has technology improved so much that simply newer must be better?

One comment upfront – the differences between the very same model of CNC machine purchased now and five years ago will not show much difference in performance except if there are major upgrades undertaken by the manufacturer or a newer generation of CNC control is standard at the time of purchase.

To simplify our exercise for comparison, we will use a newly manufactured CNC machine tool – a Vertical Machining Centre (VMC) with a 1000 mm X-travel and in available standard configuration.

Such machines are commonly sold in large numbers across all CNC machining centre markets. They are widely used for mould & die applications, semi-con parts, general engineering and parts manufacturing, medical and dental applications, aerospace applications, oil and gas, as well as military applications and other various industries.

Let us now look at the possibilities which can and will affect how a CNC machine is priced.

#1 Material And Casting Technology

Till today, most of the components in a CNC machine tool – machine bed, spindle housing, tables, columns, slides, turrets, and other components – are still made of iron casting.

Note that the differences in material composition, casting technology and process as well as the basic quality of the manufacturing process will affect machine costs. You should also take note of where the casting is produced and by which company.

Inferior materials or casting processes drastically affect the rigidity, temperature behaviour, vibration control and other differences not only during the machining of such casting parts, but more will affect the performance and quality of the finished CNC Machine.

During the manufacturing of casting parts, surface areas such as guideways, bearing seats, and other important areas need to be machined, hardened and grinded. Poor casting production and quality standard will result in flaws like air-bubbles coming up to the surface, cracks and even foreign materials like sand and stones may appear.

There are a few companies available which are able to produce quality castings for machine tools. Hwacheon Group is one of the few. Our experience over the decades taught us how to mix the right casting mixture and correctly pour the liquid casting into high quality moulds – these proven results are reflected in our machines having stable and long-lasting casting parts providing quality performances over a much longer times than competitors.

It is not surprising that castings produced at low manufacturing costs can be financially profitable even after covering the costs of transportation, custom clearance and handling charges. However, monetary benefits derived from savings in engineering does not trade off in quality and performance over the long run.

Note: Signs of poor-quality materials and casting:

• A machine bed, even of good material quality, if poorly poured and not properly altered to release tension within, will crack – sooner or later.
• Cracks in castings are not immediately visible. However, they will generate unintentional vibrations up to complete failures of your expensive CNC machine tool.
• Tool life will be shortened, followed later by poor surface finishes and reduced stability.

In short, a quality casting part is the foundation for a high quality, rigid and stable machine tool. There are no short cuts to this.

Possible Price Difference Number One

#2 CNC Control

Next, consider the types of CNC controls used in your machine tool.

A FANUC Oi looks the same in name when used on different brand of machines. However, the differences can be rather big despite the same name used.

In the industry, machine tool manufacturers can choose their required CNC Control packages and standards. Price differences often come with specification differences. Specific functions may not work or be open for use. Calculation speeds of each CNC block may vary. Look ahead functions (important for contour machining of 2D and particularly 3D work) may be missing.

The end results? Slower cutting modes and longer machining cycles.

Note: Available maximum spindle speed should match with maximum feed rates.

There will be also a price difference if Alpha or Beta motors are being used. The greater the number of axis to be controlled simultaneously, the more complex the contour of your part, the higher the demands will be from the CNC control as well as from the mechanical built of your machine tool.

Wonder why your machine “over shoots” corners?

This is due to the weak mechanical structure, design and built of your machine. Such flaws cannot be controlled by CNC control compensations. They will show their weaknesses clearly after a short span of operation, resulting in higher long-term costs. Naturally, the costs to build such machines are significantly cheaper.

In short, an accurately designed and built mechanical structure of a CNC machine tool need very little “fine tuning” by the CNC control.

Hwacheon machine tool designs are made mechanically accurate, strong and lasting. We ensure that finest accuracy in our machines through precision fine tuning and only following strict laser measuring standards.

Possible Price Difference Number Two

#3 Bearings And Spindle Design

Bearing variations are wide. Even the same brand is offering different grades of quality bearings – the right bearing for every purpose and usage.

The spindle “Heart of any CNC machine tool” alone does not make a CNC Machining Center like the Hwacheon VESTA-1000+ a different machine compared to competitors. However, the spindle is a major and important component which makes a difference in speed, rigidity and effectiveness.

All Hwacheon spindles – be they for turning or milling – are designed and built in-house and therefore have the full control in the manufacturing to produce quality spindles. The number, type and grade of bearings used, including the cooling system used are indications how well prepared is the spindle for daily production runs in the market.

Saving on a price difference of a few thousand dollars for a cheaper, weaker and inferiorly designed spindle is never worthwhile. A mechanically rigid and solidly made CNC Machining Centre with a high quality spindle makes a huge difference in performance and is well-worth the additional cost.

Possible Price Difference Number Three

#4 Guide Ways – Design And Make

There are basically two main guide way designs used for CNC Machining Centres as well as CNC Turning Centres: Solid Box Guide Ways and Linear Guide Ways (Ball type or Roller type).

Linear Roller Guide Ways are used on the Hwacheon VESTA 1000+ (this is a 1000mm market typical Machining Centre). Using this as an example, the differences in design between the two are as follows:

• Ball Guide Ways
  Used for light cutting only, they provide good speed and smooth motions due to lesser friction. However, ball guide ways do not work well when cutting harder materials or heavier machining is required. Absorption of vibrations are restricted by the “point” surface contact and pressure. Any pressure and vibration generated during cutting will come to one-point surface contact only. Naturally, such guide ways are cheaper than “Roller” type versions.
• Roller Guide Ways
  Superior to ball guide ways, roller guide ways are used for high precision machining centres and turning centres. Capable of absorbing high amounts of load pressure and vibrations, they offer smooth movements even within sub-micron movements. Hence, your machines will not experience the “stick-slip-effect”. Unlike the former, roller design provides a much wider surface contact allowing machining load and vibrations to be absorbed.

To ensure that your machine tool performance isn’t compromised, Hwacheon uses Linear Roller Guide Ways made by a reputable company in Germany on all our CNC Machines. These include the Hwacheon VESTA line of machining centres. The size and the number of blocks / shoes used on each rail varies, subject to the size and purpose of the individual machine.

The prices of Linear Roller Guide Ways can vary widely, depending on the brand, type, size, quality grade and country of origin.

Note: Products made in reputable countries and by reputable manufacturers are not priced more expensively due to high profit margins. Rather, they are more costly due to the material, quality and effectiveness results.

Possible Price Difference Number Four

The Long-Term Cost Benefits Of Paying For Quality Machines

In summary, you have learned that the material and casting used, overall mechanical design and built, bearings quality and spindle design, as well as guide ways affect the differences in CNC machine tool price. We have also explained the benefits of investing in better quality machines.

Spending a few thousand dollars more on your machine tool can give you these benefits:

• Longer tool life (up to four times longer, subjective to application and process) due to higher casting quality and machine mechanical design structure.
• Better surface quality through minimized vibrations as they are absorbed by machine casting
• Shorter cycle times as CNC control has selected faster processing time and bigger look ahead function plus through the stronger mechanical built of machine
• Stronger and more rigid spindle design with better and stable temperature control by minimized vibrations
• A guide way system which provides smooth moving by absorbing higher load and vibrations on a wider area (roller type compared to ball type)
• Bearings and Ball Screws of superb quality and from reputable manufacturer will certainly make a difference for you when used in a mechanical rigid machine design

Experienced machine tool operators know the differences between what they see in catalogues and the real machines. These differences account for why one machine is more expensive than the other.

Our customers are often pleasantly surprised with Hwacheon CNC machines. Using the same tools and the same programme, they can achieve significantly reduced cycle times with higher accuracy levels compared to their previous “lower cost and equivalent specification versions” of CNC machine tools.

The benefits of spending a few thousand dollars far outweigh the costs of having longer cycle times or shorter tool lives. As the saying goes, not the cheapest investment is the smartest investment.