Tips for Selecting a High-Precision Machining Service

High-precision machining is crucial for aerospace, automotive, and medical industries, where parts require tight tolerances. These precise components are essential for the safe and effective performance of aircraft, vehicles, medical devices, and other products. Though other methods exist to produce components, few can match the accuracy needed for these precision parts. When selecting a CNC machining partner, manufacturers should carefully consider several factors to ensure they choose the right vendor for their needs.

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Choosing the Best Partner for High-Precision Machining 

Choosing a partner for machining services involves much deliberation, but sufficient thought must go into this selection. For example, manufacturers should look at a machine shop’s areas of expertise, manufacturing capabilities, and quality control practices. Attention should also be paid to how quickly a machine shop produces and delivers parts to where they’re needed and what engineering or design services they offer in-house, if any. Additionally, the vendor’s customer service should offer sufficient support when necessary. Making an informed decision may require research, but finding a partner that best matches a manufacturer’s needs is worth it.

When picking a high-precision machining provider, consider a vendor’s: 

• Capabilities: High-end, state-of-the-art equipment and expertise are necessary for high-precision machining projects; a machine shop must have the ability and the tools to produce the necessary parts.
• Certifications: These are often relevant to certain capabilities or geared towards specific industries; for example, ISO  certification ensures the provider has a quality management system, while the AS standard is specific for the aerospace and defense sectors.   
• Customer service: While it won’t directly reflect on the quality of a machine shop’s work, companies with good customer service will be much easier to work with and will tend to come up with more advantageous solutions.  
• Lead times: The time it takes a machine shop to produce and deliver an order matters to most product manufacturers, especially if they need to meet strict production deadlines.
• Location: The distance of a part manufacturer to the facility where a product is assembled can affect the speed of production; generally speaking, choosing a domestic vendor will result in fewer delays.
• Price: The cheapest option isn’t always the best, so cost should be weighed against a vendor’s capabilities to ensure good value.
• Quality: An outsourced high-precision machining provider should have a reputation for doing quality work, so asking about previous work and references will help ascertain whether a vendor is up to the job.

Weighing these factors, a manufacturer must identify the most important for their application. For example, when cost and speed are primary motivators, a vendor’s pricing, location, and lead times are more important in any decision. In contrast, when accuracy and durability are more important, such aspects as equipment capabilities, engineering expertise, industry certifications, and quality might carry more weight. For these reasons, it’s essential to carefully consider any potential CNC machining provider to ensure they meet the needs of the project.   

Considerations for Outsourcing High-Precision Machining Projects

By asking the right questions, manufacturers can ascertain which high-precision machining vendor best fits their particular application. For specific jobs, one provider may be the best, while another vendor may prove better for another project requiring different capabilities. Often, a proven provider can recommend a suitable vendor for any secondary tasks for which they don’t have capabilities.

Many precision machining facilities specializing in specific projects will be aware of other shops that focus on other areas, which they can recommend. It thus makes sense to ask a trusted vendor for advice, even if they cannot do the job themselves. Certain high-precision machining services might concentrate on prototyping, while others concentrate on high-volume production. Some machine shops may even have capabilities that a manufacturer is unaware of, so it’s important to ask.

Component complexity also influences decisions regarding third-party vendors. Certain CNC technology offers better accuracy, so engaging a vendor with equipment that achieves tighter tolerances might be necessary. That’s why it’s important to pay attention to a vendor’s certifications and reputation among product manufacturers for producing quality parts.

Budgets and timelines are central factors in any business. Service providers must work within a manufacturer’s budget and deliver the goods on time. Yet some manufacturers can be flexible regarding lead times, with a provider able to lower costs if there’s less time pressure. However, higher prices will likely accompany stricter deadlines, so weighing the cost against production schedules is best. Recognizing the following factors will help when picking a vendor.

Expertise

Skill plus knowledge leads to expertise, though experience often augments these traits. That’s why a high-precision machining provider that’s been in business for many years is more likely to be more competent and provide better services, as they’ve already developed a reputation for reliability. While newer companies may have cutting-edge equipment, they’re unlikely to achieve the needed results if they don’t have a workforce with the right skills. This should extend beyond just the machining process to allow consideration of a vendor’s expertise in areas like customer service or order fulfillment.  

Equipment Capabilities

The key to choosing the right high-precision machining provider comes down to the capabilities of their equipment. Specialized machinery is necessary to achieve the close tolerances needed to make components with high precision. Machining services may feature automation, CNC machines with multiple axes, EDM (electrical discharge machining) machines, and other equipment, though capabilities may also include secondary services like assembly and finishing.

Methods used for high-precision machining include: 

• Waterjet cutting: For materials sensitive to higher temperatures, high-pressure waterjets for cutting enable a machinist to fabricate bevels, elaborate corners, perforated holes, and other complex geometrical structures.
• Rotary transfer machining: These machines can efficiently produce larger orders and handle big batches of both simpler and more complex components.
• Multi-axis CNC machining: By controlling the paths of multiple machine tools, these CNC machines can operate on four, five, or even more axes simultaneously, providing high-precision machining on parts to meet highly close tolerances and form them into complex geometries.
• CNC turning: Rotating a workpiece against a stationary cutting tool, computer-programmed turning operations can realize incredibly close tolerances and form complex features that include cylindrical components.
• CNC milling: Using CNC technology, this high-precision machining operation programs tool paths with CNC milling equipment to ensure consistent and accurate production.
• Laser cutting: Focusing a laser to cut through materials results in smoother edges, while the accuracy of this method allows for high-precision machining of complex shapes that conventional machines are unable to attain.
• EDM: Using electrical discharge, this subtractive process removes material from workpieces to form highly precise parts with complex geometries.

High-precision machining providers often focus on specific industries like the aerospace, defense, electronics, and medical sectors.

Material Knowledge

Regardless of the focus of a high-precision machining vendor, understanding the material’s properties with which a part is to be made is imperative. A precision machine shop should intimately understand the characteristics of not only the material out of which a part is to be made. The provider should also have general knowledge about the pros and cons of other materials. A good CNC machine company should recommend the best material for specific applications. They should also be aware of potential production issues with the materials they use and know how to address them if they arise.

Secondary Services

While a vendor’s primary services are most important, other services they offer may help a manufacturer streamline production. For this reason, it’s a good idea to inquire about a machine shop’s secondary capabilities.

Some secondary services high-precision machining companies might offer include: 

• Assembly: Some machine shops have assembly capabilities, from installing simple components to assembling complete systems.
• Finishing: Finishing processes offered might include bead blasting, coating, high-energy centrifugal deburring, grinding, magnetic spinning, manual deburring, painting, plating, thermal deburring, and vibratory tumbling; these processes can augment material properties to make parts more durable or to withstand harsh conditions.  
• Inventory management: While not part of a machine shop’s core responsibilities, certain partners can produce components in a manner that ensures manufacturers have enough parts on hand. This reduces costs, production time, and waste, making order fulfillment more accurate and organized.

Even if a service isn’t listed, many precision machine shops offer excellent secondary services through partnerships with other vendors.

Quality Control 

Controlling quality is critical in high-precision machining operations. While CNC technology generally provides a means to make parts consistently and quickly, every machining service should use robust quality control methods. A key aspect of the quality management process involves inspecting finished components for accuracy.

Basic inspection techniques a machining vendor should perform include:  

• Visual inspections to identify defective parts
• Regular quality checks during production
• In-process inspections to measure tolerances
• Guidelines for correcting production defects and errors
• Final inspections prior to delivery
• Documentation and tracking of any fabrication issues

No service provider will perform perfectly every time, so it’s also important for a CNC machine shop to provide at least satisfactory customer service.

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Customer Service

Enquiring about a precision machining facility’s customer service can reveal a lot about the company. Interactions should concentrate on building customer relationships, generally looking for a product manufacturer’s interests first. Even if the provider doesn’t have a dedicated customer service department, those who interact with customers should know the vendor’s capabilities and be able to explain these clearly. To develop and preserve relationships successfully, customers should come first, with conversations focusing on customer needs and how the machine shop can help provide for these needs rather than centering on sales.

Certifications

High-precision machining services should ideally be certified by one or more organizations that apply strict international standards to their work. These certifications provide a window into a precision machining company’s expertise, showing that a vendor is principled and pays attention to quality. As intimated earlier, certifications like ISO and AS show that a business has a quality management system and is dedicated to constantly improving its services.

ISO is globally recognized as a general standard for quality management. This standard helps high-precision machining companies initiate, employ, and sustain a quality management system while promoting continuous improvement. This certification involves establishing processes to control quality, providing guidance to help resolve customer issues, optimizing processes to improve efficiency, and continuously developing their quality management system.

The AS standard is used in the aerospace and defense sectors, building upon the quality management guidelines from ISO . This standard certifies the best precision machine shops in these industries, providing a good benchmark for the vendor’s production of quality components. A high-precision machining provider that meets AS requirements will usually offer better-quality products and superior service.

The Staub Difference for High-Precision Machining

American Manufacturing is still alive and well. There are thousands of precision machine shops across the country with an array of specialties. Most of these machine shops are drawn to the business model of high-volume production runs. Less experienced operators can run the job once it’s set up correctly, and big dollars come from each job.

As a result, it is getting harder and harder to find the right suppliers for low-volume precision machining when the job requires small batches and short runs. For the purpose of this article, I’m mainly talking about jobs of 1-50, 50-300, and 300-1,000 EAU quantities. These quantities are highly prevalent in complex industries such as Medical, Semiconductor, Defense, Printing, and others.

From the manufacturer’s standpoint, it is incredibly hard to find the right jobs, labor, and equipment to make money at the low-volume end of the business. For OEMs looking to outsource this kind of precision machining work, it isn’t easy to find a machine shop that has the capability to efficiently and effectively produce low-volume precision parts at a reasonable price. So, without further ado, I present you with some indicators that can help to identify a good low-volume precision machining partner.

1. Fast Setup Times and Continuous Setup Reduction Improvements

In low-volume precision machining, setup is everything. The setup costs are amortized across the entire batch of parts for that run. Since the parts are essentially the denominator in the equation, the lower the number of parts, the higher the cost per part.

So often the setup has more effect on the overall unit cost than the cycle time! In large production lots, this is rarely the case. But in our special situation of low volumes, the importance of a fast and efficient setup is crucial. There are many times here at PEKO where we see setup times that are far greater than the total run time of all parts. It is the nature of the business and those shops with the fastest setups and the best setup reduction improvements are going to provide the best pricing and lead times.

2. Large and Capable Inspection Department

Inspection is always a difficult bottleneck in any manufacturing process. It is slow, cumbersome, and tedious, but it must be done correctly. Today’s CMMs are highly capable but that comes with a huge price tag. Finding a machine shop with a large and capable inspection department is going to help with the cost, quality, and delivery.

Low volume production runs mean that this shop must run multiple parts to stay afloat. As such, the inspection department is running a lot of first articles to ensure production is running smoothly. This creates a bottleneck itself as the CMM must set up and run dozens of different parts per day. Make sure to take into account the capabilities of the inspection area for your low-volume precision machining supplier.

3. Robust ERP System

There’s a big difference between running 10 part numbers at 50,000 EAU versus 500 part numbers at 1,000 EAU. In low mix, high-volume production, it is relatively easy to keep processes documented and production running smoothly. In this scenario, purchasing, routing, and logistics are done at rudimentary levels.

However, for high mix, low volume production runs, things change drastically. The low-volume precision machining shop must incorporate a highly sophisticated ERP system. A snowball effect is created when the ERP and team aren’t correctly prepared for the complicated routing and purchasing procedures for each part.

4. Skilled Operators and Engineers

Having a skilled team to operate the high mix, low volume environment is absolutely crucial to success. The skill level of these employees is typically higher than their high-volume counterparts due to the nature of the work required. This includes most of the above, such as being able to do quick setups, getting parts through inspection, and understanding the ERP system.

Operators and manufacturing engineers must work together to ensure the flow is proper and that no time is wasted. When choosing a low-volume precision machining partner, ensure there is a capable and properly trained team on the job.

Remember, low volume machining is a different animal than its mid-volume and high-volume counterparts. Good precision machine shops for low volume will have similar traits, but there are critical factors that will separate them. Having great setup times, large inspection areas, a robust ERP system, and qualified personnel are the keys to success for these suppliers.

When you have a need for low-volume precision machining, how do you sort the great from the decent or not so good? To help you in evaluating and selecting an ideal partner, we’ve prepared a list of eight critical questions to ask before choosing a precision machine shop.

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