Precision & repeatability in CNC machining

by Cecile de Veyra (Managing Editor)

Image source: Getty

Machining of parts has evolved over the decades from traditional techniques done by hand to a punched-tape system or numerical control (NC) before transitioning to a computer numerical control (CNC) process.

Today, CNC technology is adopted in almost every industry because of its advantages of precision and repeatability, especially in volume manufacturing. Going by market size, CNC machines reached $81.95 billion in 2020, according to Fortune Business Insights. Grand View Research has projected that this will go up to $126.27 billion by 2028, or at 7.5 percent CAGR from 2021, attributing growth to “the rising need for minimizing operating costs and errors in machine components and increasing efficiency in manpower deployment.”

Beginning 2021, there are five trends that are expected to pave the way for its greater accessibility and reliability, according to US-based manufacturing company Fast Radius. These include the option of adding more axes even to legacy machines for fewer setups and more cost savings, and the availability of universal bases or tables and reusable soft jaws. The growing use of robotics, in particular collaborative robots or cobots, advanced workforce training through visualization software integrated in CNC machines, and upgraded CAD/CAM software are the rest.

With smart manufacturing, other technologies come into play not only to boost productivity but flexibility as well, while reducing costs in the long run. This is especially true for China, which has achieved the scale for mass manufacturing, but now has to recalibrate to also fill the need for “mass customization,” according to knowledge platform Market Prospects.

This concept is flexible manufacturing, which allows factories to shift their capacity to demand at zero cost. In this system using a computer-integrated manufacturing (CIM) approach, CNC processing centers, material storage and transportation can be managed and optimized to meet the requirement for small-batch machined parts.

Current efforts in China continue to focus on realizing this business model with equal emphasis on high precision and full automation because, despite developments in this field, Chinese companies continue to lag behind their foreign counterparts in terms of production technique and efficiency. To improve the precision of their machine tools in terms of size, shape and position, these CNC machining manufacturers are adopting error detection and compensation technology, which is said to be an effective and economical solution. They are also investing in advanced equipment, including CNC milling machines.

The range of materials used in producing CNC machined parts in China include stainless steel, copper, steel, aluminum and brass for parts.

China CNC machined aluminum parts are usually made of 6061, 6063, 6060, 2011, 7075 and 6082 alloys, while austenitic, ferritic, martensitic and duplex types are the common options in stainless steel.

For buyers looking for manufacturers that provide precision CNC machined parts, here are our recommendations.

Aluminum, with SurTec treatment

Company: Satimaco Industries Co. Ltd

Satimaco offers aluminum extrusion machining services. Its M-020 is a representative CNC machined part with SurTec 650 surface treatment for aviation applications. OEM and ODM orders are welcome.

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Any metal, finish

Company: Dongguan Foxron Precision Metal Parts Co. Ltd

For telecom equipment, the F6415 from Dongguan Foxron is a custom CNC machined part made of aluminum alloy 6061-T6, stainless steel, carbon steel, brass, copper or other material, depending on the requirement. It can have an anodized, chemical conversion including clear or yellow chromate, painted or powder-coated finish. This RoHS-compliant part is free of edges and burrs and its surface of oil, scratches and dents. QC is done using automatic CMM and a 2.5D projector to ensure 0.01mm tolerance. Price is $0.50 to $0.60. MOQ is 1,000 pieces and lead time 15 to 30 days.

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±0.002mm tolerance

Company: Mulmic Co. Ltd

Mulmic’s CNC-86 is a customized part produced using a 4-axis milling or 5-axis lathe machine. Material options include aluminum, carbon steel, alloy steel, stainless steel, brass, copper and bronze. In surface treatment, anodizing, blackening, electroplating, painting, powder coating, passivation and carburizing are some of the choices. This RoHS-compliant part, with ±0.002mm or ±0.00008in tolerance, has 0.4 RA surface roughness when milled or turned without polishing or grinding or may have a polished, mirror polished, brushed, sandblasted or heat-treated finish. Color is anodized or painted. Logos may be added using laser or CNC engraving or silk-screening. Price is $0.3 to $0.70. An order of one piece is accepted. Lead time is 10 to 12 days.

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Aluminum, custom dimensions

Company: Gambo Industry Co. Ltd

This CNC machined aluminum part, the GCN10002 from Gambo, comes in custom dimensions. It is priced $1 to $10. An order of at least 1,000 pieces is required. Lead time is between 20 and 45 days.

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±0.01mm tolerance

Company: ST Metal Manufacturer Ltd

ST Metal manufactures CNC machined parts such as the ST-1100 for bicycles. This product is made of stainless steel, copper, brass, carbon steel, aluminum or as specified using metal stamping, CNC turning, milling or machining, grinding, EDM wire cutting or die-casting. It can have an anodized, a brushed, galvanized, laser-engraved, silk-screened, polished or powder-coated surface. Tolerance is ±0.01mm. The company conducts 100 percent QC prior to shipment. Testing equipment used include CMM, toolmaker’s microscope, and automatic and manual height gauges. This part is priced $0.45 to $4.40. An order of 100 pieces is required and has a lead time of seven to 30 days.

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Turned

Company: Dongguan Mei Jie Metal Parts Ltd

The MJ-MSJ-285 from Dongguan Mei Jie is a CNC turned aluminum part. It is priced at $1 and requires an order of at least 100 pieces. Lead time is seven to 12 days. The supplier can manufacture parts for cars, bicycles, motorcycles, scooters, toy race cars, audio products, medical equipment, electronic instruments, kitchen and bathroom products and hardware parts. In addition to machining, its services include mold design, mold making, fabrication, welding, surface treatment, assembly and packing.

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