CNC Machine Shop Selection Guide

Even simple products like shafts or fasteners require a variety of machining operations, from milling to surface finishing. As complexity increases, more machining operations and equipment are needed to create the workpiece. A CNC machine shop is a space or facility that houses all the equipment and fixtures necessary to handle all subtractive manufacturing designs. This article will also explain the various mechanical and safety procedures in a machine shop. Finally, we’ll explore the advantages, applications, challenges, and how to choose the best one for your manufacturing project.

What is a CNC machine shop?

First, let’s understand the basics: What is a machine shop? It’s an enclosed space housing a variety of manufacturing equipment, machinery, tools, labor, and other necessary facilities to transform any design into a physical object. A “machine shop” refers to a subtractive manufacturing facility that utilizes a variety of advanced CNC systems and machines, from CNC milling machines to drill presses, as well as inspection equipment like coordinate measuring machines. The primary purpose of this manufacturing facility is to provide machining services tailored to the design and production needs of a wide range of industries. It can produce a wide range of parts and products, from prototyping projects for startups to large-scale production for established enterprises. Therefore, product developers can successfully bring their ideas to market or produce existing products without having to own their own CNC machining facility.

Types of Machine Tools Typically Configured in a Professional CNC Machining Shop

CNC equipment transforms the space into a machining shop. Manufacturers install and configure various equipment and mechanisms to handle the intended machining tasks. Most machine tools in this type of shop shape workpieces by removing material from the outer surface using cutting tools.While each shop may have different machine types depending on its CNC machining business model, they typically include the following CNC machines:

1. Milling Machine

CNC milling machines, or milling machines, can process a variety of materials and create shapes based on designed geometries. Machines can have 3, 4, 5, or even more axes of motion. Typically, the worktable moves along the X and Y axes to transport the workpiece to the correct position. Simultaneously, the spindle holds the cutting tool and moves along the Z axis for vertical cutting operations. In this case, the table motion also controls the feed of the rotating milling cutter. This machine is ideal for machining flat surfaces. However, it can also produce complex geometries using appropriate tools and operations, such as CNC milling, drilling, slotting, profile milling, and thread milling. However, drilling can be performed solely by a drill press or CNC drill machine. You can learn about the difference between CNC milling and drilling here.

2. Lathe

Unlike milling machines, lathes remove material by feeding a tool into a rotating workpiece. In this case, the workpiece rotates symmetrically (around its center). Therefore, lathe operations are very useful in the manufacture of cylindrical and conical parts. During lathe processing, the spindle (tool) moves across the workpiece, removing material. Simultaneously, the chuck holding the workpiece can be adjusted to align with the tool’s positioning.In addition, CNC lathes can perform CNC turning, cutting, facing, knurling, and other operations using appropriate tools.

3. Machining Center

This is an upgraded version of the milling machine, offering additional advantages in production and complex machining. Its primary difference from other CNC equipment lies in its diverse CNC machining capabilities, including milling, drilling, and tapping. Machining centers are also equipped with automatic tool changers, which reduce setup time and allow for seamless multi-operation operations on workpiece materials. Two types of machining centers can be found in the manufacturing industry based on spindle orientation:

• Horizontal machining centers
• Vertical machining centers (VMC)

Furthermore, general-purpose CNC machining centers can move the spindle in both directions to handle complex features and details.

4. Grinding Machines

In CNC machining shops, grinding machines customize the machined surface of a part to the desired dimensions and finish. They use grinding wheels to remove burrs, attached chips, and cut marks. When a rotating wheel with an abrasive surface contacts the surface of the part being machined, it removes excess or attached material, leaving a smooth surface. The grinding process can correct even minor dimensional errors in a part and achieve a mirror-like surface quality (Ra 0.02 μm). However, the final results depend on the type of abrasive and the feed control. Furthermore, the perfect combination of grinding wheel material type and grit size is crucial to achieving the desired Ra value. Grit size refers to the coarseness or fineness of the abrasive particles used on the grinding wheel.

• Low grit (10-24): Suitable for rapid material removal and roughing.
• Medium grit (30-60): Balanced, moderate material removal; commonly used in general manufacturing.
• Fine grit (80-120): For finer surface finishes and lower material removal; used for finishing operations.
• Very fine grit (150-600): Provides a very smooth surface; suitable for precision tasks and delicate surfaces.

5. Drilling Machine

This machine is known for precision deep hole drilling. It consists of a drill tool mounted on a press. The press can be equipped with mechanical, hydraulic, or automatic mechanisms. Once the drill tip contacts the surface, an attached motor system rotates the drill bit, forcing it through the material.The operator can control the pressure of the drill edge feeding down into the workpiece or use an automatic control system. Compared to CNC drilling, it can drill holes faster and easier.

6. Band Saw

Large bars, blocks, or plates cannot be processed directly with CNC machines or other processing equipment. They need to be cut to size before being shaped. Therefore, CNC machine shops are known for their ability to cut workpieces in straight and curved lines, as well as for cutting material into small pieces.Band saws operate by moving a long, flexible blade back and forth to the cutting position. During the return stroke, the blade edge applies force and ejects the material, creating the desired cut.

7. EDM Machines

Precision CNC machine shops also require EDM equipment to process hard materials and complex geometries. This equipment is compatible with extremely hard materials such as titanium and tool steel.

• Complex or precise shapes
• Sharp corners
• Undercuts
• Detailed cavities
• Various patterns
• Micromachining
• Gear tooth profiles

When the electrode contacts the workpiece, an electrical discharge is generated on the workpiece metal, removing material. Simultaneously, both the workpiece and the cutting tool (electrode) remain enclosed in a dielectric fluid.

The EDM machine generates high heat during machining, precisely melting the workpiece area to create the desired geometry. Since only conductive metals can produce electrical discharges, this machine is suitable only for conductive metals.

8. Inspection Equipment

Quality control processes ensure that machining services meet the specifications and requirements specified in the design. Therefore, every prototype and production machining shop is equipped with a variety of inspection equipment to monitor the production process and verify dimensions, tolerances, features, finish, and more.

The following are some typical inspection equipment and tools:

• Coordinate Measuring Machines (CMMs)
• Micrometers and Gauges
• Optical Comparators
• Laser Scanners
• Rockwell Hardness Testers

CMM are a popular inspection tool in every machining shop. They can measure a wide range of geometric dimensions and accuracies, alignment, surface profiles, feature locations, and more.

Comparison Between Manual and Automated Machining

Automated machining offers far greater functionality and speed than manual machining. Because CNC systems require minimal human intervention to complete their work, they improve accuracy and precision. Furthermore, CNC machines can perform multiple operations through automated control mechanisms. Furthermore, they offer greater safety than manual machining. Let’s take a look at the comparison chart below to understand the specific differences between manual and automated machining.

What is manual machining?

Manual machining is a traditional manufacturing method in which an operator directly controls the machine tool to produce the workpiece. Unlike CNC machining, manual machining does not rely on computer programs; instead, operators manually adjust various machine tool components to perform cutting, milling, drilling, and other operations. While not as precise or efficient as CNC machining, manual machining still has important applications in the manufacture of one-off parts, prototyping, and small-batch production. Manual machining typically requires experienced craftsmen who can manually operate the machine tool to perform various precision machining tasks tailored to the workpiece’s requirements. Because no programming is required, manual machining offers greater flexibility when adjusting and switching production. Currently, there are two main types of manual machining:

• Manual lathe machining: Manual lathe machining involves cutting material using a manually controlled lathe. The workpiece on the lathe is typically rotationally symmetrical, and the operator manually controls the tool’s axial and radial motion along the workpiece to remove material and form the desired shape.This machining method is widely used in the production of shafts, cylindrical parts (such as bearings), threaded parts, and rings. The advantage of manual lathe machining lies in its flexibility, making it suitable for producing small batches or custom parts.
• Manual milling: Manual milling involves milling the workpiece using a manually controlled milling machine. The milling process involves rotating a tool and moving it along multiple axes to create the desired shape. The operator manually adjusts the tool position and feed rate to control machining accuracy. Manual milling is widely used to create flat surfaces, bevels, grooves, and complex contours. It is suitable for situations requiring quick adjustments or machining individual workpieces, and is particularly advantageous in low-volume production and prototyping.

Automated machining

Automated machining is a process that uses CNC (Computer Numerical Control) systems. Machining is a manufacturing process in which preprogrammed computer software dictates the movement of factory tools and machinery. This process can be used to control a range of complex machines, from grinders and lathes to milling machines and planers. CNC machining is popular in modern manufacturing for its precision, complexity, and flexibility. It is highly scalable and suitable for prototyping and part production tasks. The CNC machining process is fully automated using preprogrammed computer software, requiring little to no human intervention. Currently, CNC machining is primarily differentiated by the type of equipment used, with three common types of equipment being common:

• CNC milling machines: CNC machining is a method that can be used to manufacture parts of any complexity. CNC milling machines use a rotating cylindrical tool to remove material from a solid block, creating custom parts for the user. The cutting tool on a CNC milling machine can move along multiple axes and rotate in the X, Y, and Z directions to mill parts. Simply put, CNC milling machines are the best way for many companies to produce high-quality, high-precision products. CNC milling machines can interpret specific commands so that the CNC system can automatically control their movement. Manual milling machines cannot do this. Using a manual milling machine can result in parts with significant errors. Furthermore, manual milling machines are difficult to operate and slow because they require more than one person to assist.

• CNC Lathes: CNC lathes are primarily used to manufacture parts according to detailed design specifications. The material in the lathe tool is clamped to the spindle and rotated with it. They are used for machining metal, thermal spraying, and turning wood. CNC lathes can also produce flat, cylindrical, or conical parts. They can also modify surface finish, weak spots, chamfered features, and the appearance of the machined part. CNC lathes make it easier to produce precisely rounded parts and reduce the potential for manual errors. Manual lathes can only produce prototypes by manually switching tools. Manual lathes can also achieve high precision, but this requires more time and effort. CNC lathes are superior to both manual and CNC lathes due to their faster processing speeds and higher precision.

• Electrical Discharge Machining (EDM): Electrical discharge machining (EDM) is a machining process that uses heat to remove material from a workpiece. Machinists can accomplish this without using mechanical force. EDM primarily uses cutting tools to create and shape complex parts. It can also produce industrial parts that are difficult to produce using milling machines or manual lathes. Compared to manual machining, EDM is the best and most efficient machining method. Using this method, EDM machines can produce more precise and higher-quality parts. The overall advantages of this process offset some of its higher costs.

Advantages of a CNC Machine Shop

For each of the industries we’ve discussed, working with a CNC machine shop offers numerous benefits. It allows businesses to produce their designs without investing heavily in machining and CNC tool setup. They simply send their designs to machine shops around the world, and they have the parts ready right there. The main advantages are:

• High Precision and Consistency: CNC machines and tooling in CNC shops produce precise and consistent products regardless of production volume. Computer-controlled mechanisms guide the cutting tools to precisely cut material. However, accuracy can vary depending on the CNC machining capabilities of a particular machine shop. This means that accuracy depends on whether the shop has low- or high-axis machines (3-, 4-, 5-, or even higher-axis machines).

• Production Speed and Efficiency: Automated control of the machining process and minimal human intervention speed up production cycles. Furthermore, with proper maintenance and care, CNC equipment can operate 24/7. High production speeds shorten lead times and reduce costs. CNC machines are typically 3 to 5 times faster than conventional machines.

• Cost-Effective Production: Optimized toolpaths in CNC machining reduce material waste and machine setup time. Consequently, minimal human intervention also reduces time. All of these factors make CNC machining a highly cost-effective method for everything from prototyping to mass production.

• Complexity and Flexibility: Tool adjustment capabilities enable handling of virtually any design type with a single setup. This allows CNC shops to machine complex geometries such as irregular contours, deep cavities, and surface details. Furthermore, manufacturers can quickly change designs with minimal cost and time to optimize production quality. It also supports customization and innovation.

The Role of CNC Machine Shops in Different Industries

Many specialized CNC machine shops produce a few specific parts. Consequently, different industries rely on different manufacturing partners to outsource their required components. Furthermore, both CNC and manual machining are used in a variety of applications, each with unique characteristics and capabilities.

CNC Machine Tools

• Aerospace: Applications include engine components, landing gear, and airframe structures.
• Automotive: Applications include engine components, transmission components, and chassis components.
• Medical Devices: Applications ranging from prosthetics to surgical instruments and implants.
• Electronics and Telecommunications: Applications include electronic housings, casings, and precision assemblies.

• Machinery and Tooling: Applications include gears, bearings, and valve components.

Manual Machines

• Prototyping and Small-Scale Production: Applications that create custom or one-off parts for various industries.
• Maintenance and Repair: Machining replacement parts for industrial equipment, machinery, and vehicles.
• Toolmaking: Custom cutting tools, molds, and dies.

Common Challenges Currently Faced by CNC Machine Shops

Like any technology, CNC machine shops have limitations and challenges. Here are some of the associated technical, operational, and economic challenges:

• High Upfront Investment: For CNC shops, the cost of not only CNC machines and other manufacturing equipment, but also quality control tools, electrical layout, tooling, and space is significantly higher than for traditional shops. However, the long-term use of these machines and tools helps lower unit costs.

• Rapid Technological Advancement: We are in an era of constant new technology in machinery, process monitoring, and tooling. Sometimes, shop owners may struggle to adapt due to a lack of expertise and investment. For example, if a shop integrated an electronic monitoring system a year ago, it now needs to update it with AI integration to remain competitive in the market.

• Operational and Maintenance Challenges: First, skilled and specialized personnel are needed.Operators in the industry are limited to performing machining tasks. Therefore, finding a skilled workforce capable of learning and adapting to new technologies is a challenge. Furthermore, maintenance costs for CNC systems and machine components are high due to the complexity, required precision, and regular software updates.

• Workshop Safety: Worker, machine, and even environmental safety are paramount for any workshop. Planning and enforcing safety rules and principles can be challenging, requiring frequent training, ongoing customization of safety equipment, routine inspections, machine maintenance, and consideration of environmental impacts.

How to Choose the Right Professional CNC Machine Shop?

Finding the right machine shop that meets your needs can save you the burden of setting up a CNC shop to produce your designs and product ideas. Therefore, when choosing a CNC shop, consider a number of factors, such as available equipment, machining accuracy, project schedule, and cost.

• Features and Services Offered: First and foremost, does the shop have the equipment and tooling to handle your design? Consider whether it’s a 3-axis, 4-axis, or 4-axis CNC machine, as well as the tolerances the machine can achieve, available materials, surface finish, and more. Next, examine the services they offer. This could be the machining processes they offer (milling, drilling, turning, etc.) or the industries they supply parts to.

• Competitive pricing: Different shops may offer different prices for the same project or design. Project specifications (such as dimensions, accuracy, timeframe, and materials) also affect cost. The goal is to find the perfect balance between quality and cost. However, you cannot compromise on the features and functionality of your target product. The best way to find a cost-effective shop is to request detailed quotes for your design from different shops and analyze their quotes and costs.

• Production Capacity and Scalability: Another factor is the CNC machining shop’s capacity and scalability. How much production can the shop deliver within a specific timeframe? If you only need a few prototypes or a small batch, can the shop or shop extend production in the future at a reasonable cost and time?

• Experience and Expertise: The primary requirement is that the shop you’re working with has similar experience. Only then can you be sure they can complete the task to specification without any errors. For example, if you need to machine aircraft engine parts, the shop must have experience working with multiple aerospace clients.

• Quality Control and Certification: Certification is crucial, especially for applications requiring compliance with specific standards, such as medical and aerospace components. To ensure a potential partner maintains stringent quality control, check for certifications such as ISO, CEN, and FDA-certified materials.

Choosing Your Professional CNC Machine Shop

Cost and precision are key factors for any CNC service, and you may want to consider establishing a manufacturing center in China for your current or upcoming projects. China’s extensive supply chain and manufacturing infrastructure make it an ideal destination for outsourced parts and products. Low labor costs, government subsidies, a dedicated workforce, extensive R&D efforts, and reliable logistics enable Chinese companies to offer significantly lower costs than those in the US and Europe.

Xtproto is a China-based manufacturing services provider with over a decade of experience producing components and products for a wide range of industries worldwide. We operate our own processing facility, equipped with 3-, 4-, and 5-axis milling, turning, and EDM machines, as well as testing equipment and surface treatment facilities. Furthermore, we offer flexible production volumes and the potential for further scalability. We are ready to assist your business. Please send us your design and we will provide you with an accurate and detailed quote.

Conclusion

In general, in today’s fast-paced market, manufacturing all parts in-house is neither feasible nor profitable for businesses. Therefore, companies can leverage the accumulated experience of various CNC machine shops to manufacture components and final products. Instead of worrying about setting up a machining facility, companies can focus on design and innovation to stay ahead in the market. Meanwhile, external manufacturers like Xtproto can provide these companies with services, producing high-quality parts at a lower cost.