When buying your CNC machine tool, what factors come into consideration? Cost? Quality? Design? Functionality? Find out the key considerations in choosing your CNC Machine in this article by Sue Neo, Hwacheon Asia Pacific.
What is the cheapest CNC machine tool which you can buy? Can you save money for your factory using affordable low-budget CNC lathes and milling machines? Or is it better in the long run to buy a premium quality CNC machine tool at a higher initial price?
There are two schools of thought here.
The first considers spending less on a machine tool to be cost-effective in reducing your overall investment and production costs. After all, these machines do cost quite a significant sum – any initial savings will help to improve overall cost effectiveness and efficiency.
The second, however, looks at the lifetime cost and better overall performance of the CNC machine tool. While cheaper machines may yield short-term savings, such machines may have higher long-term maintenance, parts replacement and other costs. They may also have limited functions, capabilities, and performance relative to premium models.
To answer this question well, let us first look at the countries of origin for CNC machine tools.
Manufacturing in Low Labour Cost Countries
Traditionally, countries with low labour costs tend to attract manufacturers of mainly mass-produced products, cheap components, or items.
While this is still true today, the rapid rise of technology has allowed high-end electronics and other consumer goods to be produced in these countries. Examples of such products include smartphones, tablets, smart televisions, fridges, automobiles, laptops, sport shoes, etc.
To keep themselves competitive, factory lines in low cost countries tend to use low cost equipment that are easier to operate. These cheaper machine tools have fewer functions and requires more customising effort on the part of the operator.
Often, machine operators in such countries tend to have lower education – their jobs are simply to load or unload parts and materials. It is also common for such firms to station one operator with one machine (after all, salaries are low and manpower is easily available).
Should crashes or incidents happen during the machining process, most likely the machine will stop. A factory supervisor will then come in to intervene. These may include tool breakages, power supply cut-off, insufficient air-supply, to the lack of raw material.
Manufacturing Norms in Industrialized Countries
Comparatively speaking, an industrialized “first-world” country tend to have higher labour, land, utility and other costs – even if they manufacture the same product, part or item as the low-cost country.
To maximise worker productivity, the CNC machine tools that you find at industrialized countries tend to be of higher grade.
Optimized for automation, they are designed for unmanned operation runs – allowing a single operator to handle multiple machines, change tools where needed, or re-set machines independently.
In such a production environment, more spindles are working at any one time. Beyond allowing for one-man operations, such machines may also have automation features such as self-loading/unloading systems, robots, tool changers, and smart software.
Due to the sophistication of these smarter multi-tasked machines, manufacturers can hire fewer operators – highly qualified specialist engineers who can handle the equipment efficiently and cost effectively, managing production runs on a 24 by 7 basis.
Key Considerations: Low-Cost vs High Quality CNC Machine Tools
Drilling down more deeply into the issue, the term “you get what you pay for” is highly relevant in the machine tool business.
For factory owners, saving thousands (or 10s of thousands of dollars) to purchase the cheapest CNC machine tool out there may actually be more expensive in the long-run. This is due to several reasons.
#1 Comparing Spindle Power, Lubrication, and Chilling Units
Low cost machines are often fitted with a less powerful spindle (e.g. 11-18 Kw motor) compared to high quality machines (e.g. a 37Kw motor). Using cheaper smaller bearings, these poorer performing spindles are usually grease-lubricated compared to the superior Air-Oil or Oil injected lubrication used in more powerful machines.
The good quality chilling units used in higher quality CNC machine tools will also provide a more stable and healthy temperature for the spindle bearing over many hours. This is much better than the simple heat exchanger unit used in cheaper machines.
Hence, spindles from higher quality machines will last longer than the cheaper machines, resulting in long-term savings for the manufacturer.
#2 Manufacturing Quality and Stability – Casting, Guideways and Ball Screw Diameters
In low cost machines, the casting is often kept small. Hence, the guideways used will not provide the same levels of stability as the more widely designed casting part used in better quality machines.
You need to also consider the materials and the methods used in manufacturing the casting of the machine. Poor quality machines are often not casted well – evidence of this includes the presence of sand, stones or air-bubbles within the casting itself.
The smaller ball screw diameters and lower quality grade used in cheap machines can also compromise both stability and life spans of the machine tool.
#3 Safety Considerations
Most importantly of all is safety.
Due to the higher safety standards in high labour cost industrialized countries, the CNC machine tools that you get from these places tend to have more safety features buffered into them.
While following higher safety standards may be more costly, you can’t really put a price tag to the well-being and lives of your people. Besides, protecting your machine operators and the people around them can also help your firm to save on insurance costs.
Checklist: Evaluating the Design and Build Quality of Machine Tools
To help you to better evaluate if the CNC machine tool that you’re purchasing is of the right quality, consider following the pointers in this simple checklist.
Rigidity of Machine
CNC machine crashes can result in significant downtime. Since cheaper machines are often less rigid, a crash can result in greater damage to your equipment. A rigid machine can also confer a better finish and tool life, and help to preserve the lifespan of the spindle.
Ball Screws, Linear Guides/ Box Ways
In low cost machines, such components may not hold up as well during crash, resulting in further repair costs. There are also cost differences between Ball and Roller Linear Guides. In addition, Box or Solid Guide Ways may also cost differently, depending on their sizes and treatment.
Accessing and Replacing Machine Parts
Have a look at the different models and see how easily can you access and replace individual machine parts. The difference between a low cost and high-quality machine is significant.
Tool Changer Design
Have a look at the designs used for the tool changer. Is it located inside the work area? How easy is it to replace the cam followers that usually break? Does it use a Cam drive or Servo drive?
As poor-quality spindle may fail more easily whenever run at high speed or a crash happens. High quality spindles tend to have not only have more and larger bearings, but they are often of better quality – these can handle more abuse over time.
Good quality spindles are also powered by more horse power, ensuring that the spindles will not stall even when large cuts are made or tough materials are used. Spindles with fewer horse power may stall or be unstable in terms of their RPM during heavy cuts. Belt-driven spindles (the cheaper kind) may also stall during such operations.
Due to the consistent speed of high-quality spindles, the finish of the part will be better with higher Rpm. This will also result in a longer tool life and savings in cycle time.
Do check for tighter tolerances in your machine – these normally translate into a longer life and smoother operation.
How Service Readiness Affects CNC Machine Tool Pricing
Last, but certainly not least, you need to consider the after-sales and ongoing services offered by your CNC machine tool manufacturer or supplier.
Here are some important factors to think about:
- Wait time for service technician: How closely located is your supplier / dealer? If they take over 1.5 hours to response or travel to your location, the time taken to get your machine fixed can be excruciatingly long.
- Quality of service technician: This is a major consideration. As technology becomes more complex, factory trained engineers and knowledge of service engineers are crucial. Information and support from manufacturers are also essential.
- Warranty of parts: When it comes to warranties of parts being replaced, you will need to get them from your supplier / dealer. This may include the replacement of spindles or calibration jobs.
- Parts availability: Does your dealer / supplier operate from a predictive or reactive position? Are spare parts available readily or easily?
- Supplier / dealer response time for information and parts: For some suppliers / dealers it takes at least a day or two to get parts or information from the manufacturer through the dealer. This has to be factored into your production plans.
As you can see from our detailed analysis above, there are many factors which you need to consider when you purchase a CNC Machine Tool.
While a low price may be attractive from the onset, the long-term headaches and costs incurred in repairs and replacements may outweigh any initial cost savings.
Over the long run, companies which invest in good quality equipment, tooling, and accessories – plus invest from time to time in training their staff in the latest techniques – will stand to enjoy greater cost effectiveness and efficiency in their manufacturing operations.
Ready to maximise the yield from your shop floor? Visit our website or contact us for recommendations on the right machine tools to improve your productivity and cost-effectiveness over the long-term.
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