Role of CNC Machines in Reducing Manufacturing Costs

One of the most impactful contributions of CNC machines is helping reduce overall manufacturing costs. CNC machines  provide a solid platform for improved speeds, feeds, and repeatable accuracies. The use of CNC machines in manufacturing has been transformative. There are many measurable positive effects of this CNC transformation, and its consequences, but the overriding end product is efficiency and it is these gained efficiencies that ultimately reduce manufacturing costs. Closely associated with these efficiencies are opportunities to reduce labor costs, expand application of automation and decrease scrap rates.

Accuracy and Reproducibility

One of the most significant advantages of CNC machines is their  accuracy and repeatability.  CNC machines are capable of reproducing parts consistent in size shape and tolerance, once the CNC program is finalized and tool setup is complete. This consistency is not dependent on operator skill levels. The machines will produce uniform precision parts. To further increase accuracy, the latest generations of CNC machines have internal tool life monitoring and inline gauging. These two features give the machine the ability to monitor cutting forces and automatically make adjustments to feeds and speeds, thus prolonging tool life and minimizing tool wear.

Scrap Reduction

In manufacturing one area for cost reduction is minimizing scrap. Prior to the introduction of CNC machines, machining was achieved via manual operation. Manual machinist could be very experienced and skilled, but producing precision parts repeatably, was difficult and slow. Scrap rates were dependent on the experience and skill level of the operator.  The availability of  skilled labor is always in short supply. Factoring in the shortage of skilled labor  and a higher labor cost with higher scrap rates, decreases efficiency, lessens throughput and adds to the overall costs.

CNC machines are far less dependent on operator skill level. There are other operator skill sets required (setup, basic machining knowledge, etc.), but  the primary  component accuracies are derived  from the efficiency of the machine program, proper tooling and stability of the machine platform. These factors do not eliminate errors (i.e. scrap) but they can substantially reduce dimensional mistakes and minimize scrap.

In a CNC machine, once a program and tooling have been proven out, the machine can be run at much higher rates of feeds and speeds, greatly increasing throughput. The efficiencies gained  are significant.

Automation

Almost all CNC machines implement some level of automation. Basic CNC machines have automatic tool changers (mills), turrets that hold different tools for different operations (lathes), or a combination of both (turn/mills). Part  load/unload devices (robotics) can be easily added and incorporated into the machining process. Also folded into the automation process is inline gauging for measuring tool lengths/diameters, and gauging for part measurement. This information is recorded and interfaced  through the CNC controller. Depending on batch sizes and tooling life, some automation can run a complete 8 hour shift with minimal operator involvement. Automation allows for machines to run through lunch and coffee breaks. Spindle utilization is optimized. There certainly are  costs to consider, in the  justification of automation,  but  taking direct labor cost out serves as a strong incentive.

Setup & Changeover

A real value of CNC machines is flexibility. Because of their design they can be utilized for prototype/ short run and also high production. Most of the programming is done offline via CAD/CAM. The CAD generates toolpath around part shape. The CAD information is then downloaded into a CAM system. The CAM generates the G&M codes necessary for the machine controller to read. Changes/edits can easily be made in the programs  either at the machine or offline in the CAM software. Most machines share common tools and have adequate tool storage to run multiple parts. This shortens setup and helps minimize changeover times, helping reduce part cost.

Because the machine is programmable, axes movements and spindle speeds are controlled through the CNC controller. This feature gives the machine the ability to generate very complex shapes without having to use  special ground form tools. The shapes  generated through the controller use standard tooling. This feature shortens lead times and can eliminate the purchase of expensive form tools.

Minimizing inventory costs

Because of flexibility, CNC machines can play a significant role in helping control inventory costs. Modern aerospace component manufacturing is driven by short lead times. One solution that addresses this issue would be to increase inventory, but with shrinking profit margins, multiple rev. changes  and concern of carrying cost, this is not a viable alternative. Although not a complete solution, utilizing the flexibility of CNC machines, with the benefits described above (accuracy, setup, scrap reduction, reduced setups), all factors that provide real options and opportunities for reducing inventory costs.

Conclusion

We at Intrex Aerospace are committed to continued investment in CNC machines. In the last 5 years we have purchased multiple pieces of CNC equipment, totally in the millions of dollars. We know that these types of focused investments, enable us to provide a higher level of quality parts and also through efficiencies gained, help reduce our manufacturing cost.

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