CNC milling and turning are the most commonly used processes in modern manufacturing. While they offer unparalleled precision and automation, they differ in efficiency and cost implications. CNC milling is ideal for complex parts but involves higher machine and programming costs. On the other hand, CNC turning is optimized for cylindrical parts. It offers reduced material waste and operating expenses.
As a seasoned manufacturer or one just starting, understanding the cost efficiency of CNC milling and turning is essential to help you stay competitive. This article will discuss the cost efficiency of a CNC mill vs a CNC turn. It will cover CNC machining costs, cycle time, material waste, and labor costs.
CNC Mill Overview and Cost
Milling is a precision CNC machining operation where a rotating cutting tool removes material gradually from a stationary workpiece. The result is a component that looks exactly like the original design. The CNC mill is accurate and very versatile. It is compatible with many engineering materials and can produce complex geometries with extremely tight tolerances.
CNC milling machines range from 3-axis to 5-axis and beyond. The multi-axis capabilities allow for complex part machining in a single setup. CNC mills can be expensive, especially for those just starting. The cost of milling is influenced by many factors dependent on one another. The machine and maintenance costs vary extensively.
CNC Turn Overview and Cost
Turning is another process that falls under the broad CNC machining operation. It is a subtractive process that uses a rotating workpiece and stationary cutting tool to shape cylindrical and conical parts. You carry out CNC turning with a lathe or turning center that spins the workpiece while the cutting tool moves linearly. The process is repeatable, and the machine runs for hours with minimal human intervention.
CNC turn is best suited for fasteners, automotive brake systems, and orthopedic implants. Furthermore, it is a cost-efficient manufacturing method. However, you have to put proper measures in place to sustain affordability.
Cost Comparison: CNC Mill vs Turn
Cost is a significant distinction between CNC milling and turning. When evaluating these processes for cost efficiency, you should consider several factors, including material waste and cycle time. Below is an extensive discussion on the differences between CNC mill and turn.
Initial Investment Costs
The upfront costs and initial investment are significant distinctions between milling and turning. This entails all the expenses incurred when purchasing and installing the machine and any accessories. Generally, the basic model of CNC mills costs more than that of CNC turning machines. However, the cost still depends on the particular type you want to work with. The price becomes similar for high-end models.
Furthermore, CNC turning machines are easier to install. On the other hand, CNC mills may require special foundations for heavy duty models.
Operating Costs
You can also differentiate between CNC mill and turn based on the operating costs. The cost-effectiveness of each process depends on labor and energy consumption. CNC milling requires skilled operators. It comes with more labor costs ranging from $25 to $60 per hour for machinists.
This is a little lower for CNC turning and is between $20-$50 per hour. The energy the processes consume also differs. CNC milling consumes higher energy, while CNC turning is more energy efficient. This is because the tool remains stationary while the workpiece rotates in CNC turning.
Maintenance and Repair Costs
CNC turning and milling machines require regular maintenance to function optimally. However, there is still a difference. Based on machine usage, the average maintenance costs of CNC mills are $5,000 to $15,000. This covers lubrication and coolant maintenance systems.
On the other hand, you should expect to spend $3,000 to $10,000 yearly when using CNC lathes. Turning spindles last longer than milling spindles. Additionally, you don’t have to replace cutting tools and machine parts frequently because of the lower cutting force.
Tooling Costs
You can also analyze the cost efficiency of CNC milling and turning based on tooling expenses. End and face mills are relatively expensive. The frequent tool changes associated with CNC mills also increase costs. For the monthly tooling costs of CNC milling, the budget is usually between $2,000 and $10,000.
This is different for CNC turning. The tools used are less expensive than milling setups. Additionally, CNC turn work holding fixtures are more affordable than custom milling fixtures. Therefore, the average monthly tooling costs are usually between $1,000 to $5,000.
Programming and Setup Costs
A CNC mill’s programming and setup costs differ from that of a CNC turn. CNC milling requires extensive programming, especially for complex parts with intricate designs. This cost increases as the number of machine axes increases. The hourly programming costs can range between $50-$150 depending on part complexity.
On the other hand, CNC turning is easier to set up and program because it primarily involves rotational motion. It needs simpler and fewer tool paths. CNC turning programming costs are lower, usually $30-$100 per hour.
Material Waste and Scrap Generation
The material waste and rate of scrap generation significantly affect production costs. This is especially true when using expensive materials like titanium and stainless steel. CNC milling and turning generates high waste because of their subtractive nature.
However, there is more waste and scrap gotten from CNC milling operations. You need to remove a large amount of material to shape the final part in milling. The material lost as chips is recycled using an expensive process. Additionally, chips generated in CNC turning are more uniform and more straightforward to recycle.
Cycle Time
The production speed per part is another way to differentiate between a CNC mill and a turn. Cycle time is crucial for cost efficiency as you may get lower per-unit costs when production is fast. Several factors affect milling speed. Some include toolpath optimization, number of operations, and multi-axis machining. However, the average cycle time for a CNC mill is 5-30 minutes.
This is considerably higher than the CNC turn, which is between 1-10 minutes. CNC turning is faster for symmetrical parts because the workpiece rotates at high speeds. You produce more parts per time when compared to CNC milling.
Training and Operator Cost
You should also compare CNC mill and turn based on the wages. CNC milling requires highly skilled operators. They must have basic CNC knowledge and an in-depth understanding of multi-axis programming, work holding, and tooling selection. Because of this broad knowledge base, experienced CNC mill operators charge between $20 to $60 per hour.
On the other hand, CNC turning is easier to carry out, and the programming tasks are straightforward. It is more cost-effective regarding training, and the hourly pay is an average of $20-$50.
Table 1: CNC Milling Vs. CNC Turning: Cost Efficiency Comparison
| Parameters | CNC Milling | CNC Turning |
| Programming and Setup Costs | More complex programming and longer setup time. | Simpler programming and shorter setup time. |
| Material Waste and Scrap Generation | High material waste (20-30%). | Low material waste (<15%). |
| Cycle Time | Slow production for complex parts. | Faster production, especially for asymmetrical components. |
| Training and Operator Costs | Requires highly skilled operators for multi axis machining. | Easier to learn and lower skill requirements. |
| Cutting Tool Costs | Higher tooling costs. | Lower tooling costs. |
| Maintenance and Repair Costs | Higher. | Lower. |
| Cycle Time | The average cycle time for a CNC mill is 5-30 minutes. | The average cycle time for CNC turn is 1-10 minutes. |
| Operating Costs | $25-$60 per hour for machinists | $20-$50 per hour. |
Conclusion
CNC milling and turning are expensive operations, especially for those just starting. However, the milling process is generally more costly than turning because of the CNC machine price. There are some cost-saving strategies one can employ to reduce expenses and make maximum use of your investment. Always choose the right cutting tools and inserts to improve efficiency and minimize downtime. You should also automate processes to reduce manual interventions and labor costs.
