CNC Machining Services for Precision Stainless Steel Components and Custom Parts

CNC Machining Services for OEM Industrial Components

CNC machining plays an important role in modern manufacturing by providing accurate, flexible, and repeatable production solutions for customized components.

For OEM customers requiring stainless steel parts, precision mechanical components, and non-standard industrial products, selecting the right CNC machining supplier is critical to achieving consistent quality and reliable production.

Welle Fasteners provides precision CNC machining services for stainless steel components, custom metal parts, and OEM manufacturing projects. In addition to CNC machining, Welle specializes in custom stainless steel fasteners for OEM industrial applications.

By combining CNC turning, CNC milling, secondary processing, and surface finishing capabilities, Welle supports customers from prototype development to small batch production and long-term manufacturing programs.

What Is CNC Machining?

CNC (Computer Numerical Control) machining is a precision manufacturing process that uses computer-controlled machines to remove material from a solid workpiece and create components with accurate dimensions, complex geometries, and controlled surface finishes.

Unlike additive manufacturing processes such as 3D printing, CNC machining creates parts through controlled material removal. Compared with traditional forming processes that require dedicated tooling, CNC machining provides greater flexibility for customized components, prototypes, and low-to-medium volume production.

The CNC machining process starts with a digital CAD model created according to the customer’s design requirements. The CAD data is converted into CNC programs that control cutting tools and machining operations, allowing manufacturers to produce consistent and repeatable components with high dimensional accuracy.

CNC machining is widely used for precision industrial parts because it can process a broad range of engineering materials, especially metals such as stainless steel, carbon steel, alloy steel, and aluminum. The technology is commonly applied for manufacturing customized mechanical components, housings, shafts, threaded parts, and other precision-machined products.

The two primary CNC machining processes are CNC milling and CNC turning. CNC milling uses rotating cutting tools to remove material and create complex shapes and features, while CNC turning rotates the workpiece against cutting tools to produce cylindrical components with precise dimensions.

For OEM customers requiring customized metal components, CNC machining provides an effective solution by combining design flexibility, material versatility, and reliable production accuracy.

CNC Machining Processes and Equipment Capability

CNC machining can be performed using different machine configurations depending on part geometry, material requirements, production volume, and required precision.

At Welle Fasteners, CNC machining processes are selected based on the specific requirements of each component, ensuring the right balance between accuracy, efficiency, and cost.

CNC Turning

CNC turning is commonly used for cylindrical and rotational components.

During the turning process, the workpiece rotates while cutting tools remove material to create the required dimensions and features.

Typical CNC turning applications include:

• Shafts
• Bushings
• Threaded components
• Precision mechanical parts
• Custom fastener components

CNC turning provides excellent efficiency for rotational parts requiring accurate diameters, threads, and surface finishes.

CNC Milling

CNC milling uses rotating cutting tools to remove material from a fixed workpiece.

It is suitable for producing components with complex geometries, flat surfaces, slots, holes, and multiple machining features.

Typical applications include:

• Machine components
• Housings
• Brackets
• Custom metal parts

CNC milling provides flexibility for prototype development and small-to-medium production of customized components.

Multi-Axis CNC Machining

For components requiring complex geometries or reduced machining setups, multi-axis CNC machining provides additional flexibility.

Advanced CNC systems allow cutting tools or workpieces to move across multiple axes, enabling manufacturers to produce more complex features with improved accuracy.

Multi-axis machining is commonly used for:

• Complex industrial components
• Precision mechanical parts
• Components requiring multiple machining angles

The appropriate machining configuration depends on part complexity, tolerance requirements, production volume, and cost considerations.

CNC Mill-Turn Machining

Mill-turn CNC systems combine turning and milling capabilities in one machining platform.

This approach allows manufacturers to complete multiple operations in a single setup, reducing repositioning requirements and improving production consistency.

Mill-turn machining is suitable for components requiring both:

• Rotational features;
• Milled or drilled features.

Benefits and Limitations of CNC Machining

CNC machining is widely used for customized industrial components because it provides excellent accuracy, material flexibility, and production versatility.

However, understanding both the advantages and limitations of CNC machining helps engineers and buyers select the most suitable manufacturing solution for their applications.

Benefits of CNC Machining

CNC machining is widely used for customized industrial components because it provides excellent accuracy, material flexibility, and production versatility.

However, understanding both the advantages and limitations of CNC machining helps engineers and buyers select the most suitable manufacturing solution for their applications.

Benefits of CNC Machining

Limitations of CNC Machining

Selecting the Right CNC Machining Process

At Welle Fasteners, the machining process is selected based on engineering requirements rather than equipment capability alone.

Our engineering team evaluates:

• Part geometry;
• Material selection;
• Required tolerances;
• Surface finishing requirements;
• Production quantity.

By selecting the appropriate CNC machining method, Welle helps customers achieve reliable quality, efficient production, and consistent performance for customized components.

CNC Machining Capabilities at Welle Fasteners

Welle Fasteners provides precision CNC machining solutions for customers requiring customized metal components with specific dimensional and performance requirements.

Our CNC machining capability includes:

CNC Turning

CNC turning is suitable for producing cylindrical and rotational components requiring high dimensional accuracy.

Typical applications include:

• Shafts
• Threaded components
• Bushings
• Precision mechanical parts

CNC Milling

CNC milling provides flexibility for complex geometries and multi-feature components.

Applications include:

• Housings
• Brackets
• Machine components
• Customized metal parts

Multi-Axis CNC Machining

For components requiring complex features and improved machining efficiency, multi-axis CNC machining provides additional flexibility.

It is suitable for:

• Complex geometries
• Reduced setup requirements
• Precision industrial components

Welle manufactures precision CNC machined components according to customer drawings and specifications.

Stainless Steel CNC Machining Capability

Stainless steel is widely used in industrial applications because of its corrosion resistance, durability, and mechanical performance.

However, machining stainless steel requires appropriate tooling, cutting parameters, and process control to achieve stable quality.

Welle Fasteners supports CNC machining of stainless steel materials including:

Stainless Steel 304

Suitable for general industrial applications requiring good corrosion resistance and machinability.

Common applications:

• Industrial equipment
• Machinery components
• General mechanical parts

Stainless Steel 316/316L

Selected for applications requiring improved corrosion resistance.

Typical applications:

• Marine equipment
• Food processing systems
• Chemical equipment

17-4PH Stainless Steel

Used where higher mechanical strength is required.

Applications include:

• Precision machinery
• High-load components
• Industrial systems

CNC Machining Tolerances and Quality Control

For OEM customers, machining accuracy directly affects assembly performance and product reliability.

Welle applies strict quality control for custom components  to ensure dimensional accuracy and production consistency.

Quality considerations include:

• Dimensional accuracy
• Thread requirements
• Surface condition
• Assembly compatibility

Inspection methods may include:

• Dimensional measurement
• Thread inspection
• Surface inspection
• Quality documentation

For precision components, maintaining consistent production quality is essential for reliable long-term supply.

CNC Machining Design Guidelines for Better Manufacturing Results

When developing CNC machined components, early design consideration can improve manufacturability and cost efficiency.

Important factors include:

• Material selection
• Part geometry
• Wall thickness
• Machining accessibility
• Tolerance requirements
• Surface finish requirements

Working with an experienced CNC machining supplier during the design stage can help identify potential manufacturing challenges before production.

Understanding fastener drawing requirements helps engineers and buyers communicate specifications clearly with manufacturers.

In less than 15 minutes, you will learn all you need to know to design parts optimized for CNC machining: from Design for Machinability rules to cost reduction tips and from material selection guidelines to surface finishing recommendations

CNC machining design restrictions

The design restrictions in CNC machining are a natural result of the mechanics of the cutting process and in particular:

Tool geometry

Most CNC machining cutting tools have a cylindrical shape with a flat or spherical end, restricting the part geometries that can be produced.

For instance, the internal vertical corners of a CNC part will always have a radius, no matter how small a cutting tool is used.

Tool access

Surfaces that cannot be reached by the cutting tool, cannot be CNC machined.

This prohibits, for example, the fabrication of parts with internal ‘hidden’ geometries, and puts a limit to the maximum depth of an undercut.

Workpiece stiffness

Due to the cutting forces and the temperatures developed during machining, it is possible for the workpiece to deform or vibrate.

This limits, for example, the minimum wall thickness that a CNC machined part can have and the maximum aspect ratio of tall features.

Tool stiffness

Like the workpiece, the cutting tool can also deflect or vibrate during machining. This results in looser tolerances and even tool breakage.

The effect becomes more prominent when the ratio of length-to-diameter of the cutting tool increases and is the reason why deep cavities cannot be easily CNC machined.

Workholding

The geometry of a part determines the way it will be held on the CNC machine and the number of setups required. This has an impact on the cost, but also the accuracy of a part.

For example, manual repositioning introduces a small, but not negligible, positional error. This a key benefit of 5-axis versus 3-axis CNC machining.

Design rules for CNC machining

In the table below, we summarise how these restrictions translate into actionable design rules.

Cavities & pockets

Recommended depth: 4 x cavity width

Feasible depth: 10 x tool diameter or 25 cm (10’’)

Deeper cavities need to be machined with cutting tools with larger diameter affecting the fillets of the internal edges.

Internal edges

Recommended: larger than ⅓ x cavity depth

For internal vertical edges, the larger the fillet the better.

Edges on the floor of a cavity should be either sharp or have a 0.1 mm or 1 mm radius.

Minimum wall thickness

Recommended: 0.8 mm (for metals)

Feasible: 0.5 mm

Recommended: 1.5 mm (for plastics)

Feasible: 1.0 mm

Decreasing the wall thickness reduces the stiffness of the workpiece, increasing vibrations and lowering the achievable tolerances.

Plastics are especially prone to warping and thermal softening, so a larger minimum wall thickness is necessary.

Holes

Recommended diameter: standard drill bit sizes

Recommended depth: 4 x nominal diameter

Max. depth: 10 x nominal diameter

Holes with standard diameter are preferred, as they can be machined with a standard drill bit. Blind holes machined with a drill will have a conical floor.

Holes with non-standard diameter will be machined with an end mill tool and should be treated as cavities (see previous rule). Blind holes machined with an end mill tool will be flat.

Threads

Recommended length: 3 x nominal diameter

Recommended size: M6 or larger

Feasible size: M2

Choose the largest thread possible, as they are easier to machine. Threads longer than 3 times the nominal diameter are unnecessary.

Always design threads as cosmetic in your CAD package and include a technical drawing to your order.

Tall features

Recommended max. ratio: height / width < 4

Tall features are difficult to machine accurately, as they are prone to vibrations. Consider the overall geometry of the part: rotating the part by 90° degrees during machining changes the aspect ratio.

Small features

Recommended: 2.5 mm (0.100’’)

Feasible: 0.50 mm (.020’’)

Cavities and holes down to 2.5 mm (0.1’’) can be CNC machined with standard cutting tools. Anything below this limit is considered micro-machining and must be avoided unless necessary.

Tolerances

Standard: ± 0.125 mm (.005’’)

Feasible: ± 0.025 mm (.001’’)

Tolerances (unilateral, bilateral, interference or geometric) should be defined on all critical features, but DO NOT over-tolerance.

If no tolerance is specified in the technical drawing, then the standard ± 0.125 mm will be held.

Maximum part size

CNC milling: 400 x 250 x 150 mm (typically)

CNC turning: Ø 500 mm x 1000 mm (typically)

Very large CNC machines can produce parts with dimensions up to 2000 x 800 x 1000 mm ( 78’’ x 32’’ x 40’’).

5-axis CNC machining systems typically have a smaller build volume.

Designing undercuts

Undercuts are features that cannot be machined with standard tools, no matter how the part is rotated, because the cutting tools cannot access all surfaces. If square aluminum extrusions were manufactured with CNC machining, then their grooves would be considered undercuts.

Undercuts can be machined using special T-shaped, V-shaped or lollipop-shaped cutting tools if designed correctly.

Here are some practical guidelines to help you get started with designing undercuts.

Undercut dimensions

Recommended width: 3 mm (1/8’’) to 40 mm (1 ½’’)

Max. Depth: 2x width

Design undercuts with a width of whole millimeter increments or a standard inch fraction. For undercuts with non-standard dimensions, a custom cutting tool must be created.

The standard tools have a cutting depth of approximately two times their width. This limits the achievable depth.

Undercut clearance

Recommended min. clearance: 4x depth
For undercuts on internal faces, add enough clearance between the opposing walls to ensures tool access.

CNC Machining Materials

CNC machining can be used with a very wide range of engineering metals & plastics.
In this section, you will learn more about the key characteristics of the most popular materials. We will also examine the most common finishes that are applied to CNC machined parts.

Material choices

Selecting the right material is a crucial step in the design process. The optimal material option is highly dependent on your specific use case and requirements.

Since almost every material with sufficient hardness can be machined, CNC offers a very large range of material options to choose from. For engineering applications, metals and plastics are most relevant and will be the focus of this section.

Surface finishes can also alter the properties of CNC machined parts and we will examine them below.

To get started, take a look at this decision tree. It contains high-level material recommendations that cover the most common design requirements.

Metals

CNC machining is primarily used with metals and metal alloys. Metal can be used for both the manufacturing of custom one-off parts and prototypes and for low-to-medium batch production. Aluminum 6061 is by far the most used material in CNC machining.

Aluminum Alloys

• Properties: Excellent strength-to-weight ratio, high thermal and electrical conductivity, and natural corrosion resistance.
• Common Grades: 6061, 7075, 5052, 8011

Stainless Steel

• Properties: High strength, excellent ductility, outstanding wear and corrosion resistance; can be welded, machined, and polished.
• Common Grades: 304, 316, 2205, 17-4 PH

Alloy Steel

• Properties: Improved hardness, toughness, fatigue, and wear resistance compared to mild steels; low chemical resistance.
• Common Grades: 4140, 4340

Mild Steel

• Properties: Cost-effective, good mechanical properties, easy to machine and weld; suitable for general use.
• Common Grades: 1018, 1045, A36

Tool Steel

• Properties: Exceptionally high hardness and stiffness, excellent abrasion and thermal resistance; ideal for dies, stamps, molds, and other industrial tooling.
• Common Grades: D2, A2, C0, O1, O10

Brass

• Properties: Excellent machinability and low friction; aesthetically appealing golden color.
• Common Grades: C360

Plastics

Plastics are lightweight materials with a wide range of physical properties. They are often used for their chemical resistance and electrical insulation properties. Plastics are commonly CNC machined for prototyping purposes prior to Injection Molding.

ABS (Acrylonitrile Butadiene Styrene)

• Properties: Lightweight thermoplastic with good mechanical properties and excellent impact strength; widely used for general-purpose applications.
• Common Grades: Standard ABS

Polycarbonate (PC)

• Properties: Excellent impact strength, high thermal resistance, and toughness; can be colored or transparent, suitable for outdoor applications.
• Common Grades: PC1

Nylon

• Properties: General-purpose engineering thermoplastic with good mechanical properties and excellent chemical resistance.
• Common Grades: Nylon 6

POM (Delrin)

• Properties: Easy-to-machine engineering thermoplastic with high stiffness, excellent frictional characteristics, and good thermal stability.
• Common Grades: Delrin

PEEK (Polyether Ether Ketone)

• Properties: High-performance engineering thermoplastic for the most demanding applications; excellent mechanical and thermal properties.
• Common Grades: PEEK

Surface finishes of CNC Parts

Surface finishes are applied after machining and can change the appearance, surface roughness, hardness and chemical resistance of the produced parts. Below is a quick summary of the most common finishes for CNC.

As-machined

As-machined parts have the tightest tolerances, as no extra operations are performed on them. Marks following the path of the cutting tool are visible though.

The standard surface roughness of as-machined parts is 3.2 μm (125 μin) and can be reduced to down to 0.4 μm (16 μin) with further operations.

Bead blasting

Bead blasting adds a uniform matte or satin surface finish on a machined part, removing all tool marks.

Bead blasting is mainly used for aesthetic purposes, as the resulting surface roughness is not guaranteed. Critical surfaces or features (like holes) can be masked to avoid any dimensional change.

Anodizing (clear or colored)

Anodizing adds a thin, hard, non-conductive ceramic coating on the surface of aluminum parts, increasing their corrosion and wear resistance.

Critical areas can be masked to retain their tight tolerances. Anodized parts can be dyed producing a smooth aesthetically pleasing surface.

Hardcoat anodizing

Hardcoat anodizing produces a thicker, high-density ceramic coating that provides excellent corrosion and wear resistance.

Hardcoat anodizing is suitable for functional applications. The typical coating thickness is 50 μm and usually, no color is applied. Critical areas can be masked to retain their tight tolerances.

Powder coating

Powder coating adds a thin layer of strong, wear and corrosion resistant protective polymer paint on the surface of a part.

It can be applied to parts of any material and is available in many colors.

Silk screening

Silk screening is an inexpensive way to print text or logos on the surface of CNC machined parts for aesthetic purposes.

It can be used in addition to other finishes (for example, anodizing). The print can be applied only to the external surfaces of a part.

Surface Finishing Options for CNC Machined Stainless Steel Parts

After CNC machining, additional surface finishing processes may be required to achieve required appearance, corrosion resistance, or functional performance.

Welle provides finishing solutions including:

• Passivation
• Electropolishing
• Mechanical polishing
• Bead blasting

These finishing processes help improve:

• Corrosion resistance
• Surface cleanliness
• Appearance consistency
• Product reliability

From Prototype Development to Production Manufacturing

Different projects require different manufacturing approaches.

Welle supports OEM customers through multiple development stages:

Prototype development → Small batch production → Long-term manufacturing

This approach helps customers:

• Validate designs
• Optimize manufacturing processes
• Reduce development risks
• Establish reliable supply chains

CNC Machined Component Applications

One of the greatest things about CNC machining is the wide range of applications it has found over the years.

Here, we collected some recent examples to illustrate how professionals have exploited the benefits of CNC machining to get the best results in different industrial situations. Use them as inspiration for your projects.

Space

CNC machining is one of the very few manufacturing processes that is suitable for creating parts for space applications. Not only because of CNC parts have excellent accuracy and material properties, but also due to the wide range of surface treatments that can be applied to the parts after machining.

Aerospace

Aerospace was one of the first industries to use CNC machining. This is due to its ability to manufacture lightweight parts with excellent physical properties and very tight tolerances. CNC machining is used both for aircraft parts and also during the development stages.

Automotive

CNC machining has applications in the automotive industry when manufacturing of high-performance custom parts is required.

Product Design & Development

The ability of manufacture quickly custom metal parts with great dimensional accuracy, makes CNC machining an attractive option for producing functional prototypes. This is essential during later stages of design and development.

Electrical & electronic manufacturing

CNC machining has many applications in the electrical and electronic manufacturing industry: from the prototyping of PCBs to the manufacturing of enclosures.

Tooling & Industrial manufacturing

A very common industrial application of CNC machining is the fabrication of tooling for other processes. For example, the molds in Injection Molding are commonly CNC machined from aluminum or tool steel.

Sports & motorsports equipment

High-performance sports & motorsports manufacturers always try to increase the performance of their products by reducing their weight.

Why Choose Welle Fasteners for CNC Machining?

Welle Fasteners is a trusted precision fastening solutions provider with extensive experience in CNC machining and custom fastener production. Our engineers meticulously analysis your technical drawings and specifications to deliver high-quality, reliable mechanical components tailored to your project needs.

By combining advanced CNC technologies—including 3, 4, and 5-axis machines—with our skilled operators, we ensure consistent dimensional accuracy, superior mechanical performance, and defect-free results. All production is carried out in-house, allowing complete control over quality and timely delivery.

We support global engineering teams with precision component manufacturing and on-site supplier quality control according to ISO and IATF standards.

Over the past years, we have helped customers develop 500+ mechanical components per year, including:

●Heat-treated parts (HRC 58-62)

●Complex 5-axis machined components

●High-precision parts (±0.002 mm)

●Mirror-polished & surface-coated components

●Mechanical assemblies

●NDT & leak-testing parts

Engineering Support

Welle supports customers from drawing review to production implementation.

Support includes:

• Manufacturing feasibility review
• Material selection
• Process recommendation
• Surface finishing guidance

Our key services include:

●Medium-batch & high-precision manufacturing for new projects and prototypes

●NPI supplier evaluation & quality monitoring directly in China

●Lead-time and logistics risk management for stable deliveries

By combining inspection and manufacturing, we help customers reduce risks, improve supplier performance, and keep projects on schedule.

Integrated Manufacturing Capability

Welle provides:

Engineering Review

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Material Selection

↓

CNC Machining

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Secondary Processing

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Surface Finishing

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Quality Inspection

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Delivery

OEM Manufacturing Experience

Welle supports:

• Prototype projects
• Small batch production
• Long-term OEM supply

Need Custom CNC Machined Components?

Send your drawings or CAD files to Welle Fasteners.

Our engineering team can help evaluate:

• Manufacturing feasibility
• Material selection
• Machining process

Surface finishing requirements