In the world of CNC turning, the role of tolerances cannot be emphasized enough. These tolerances are the key to achieving the highest levels of accuracy and precision in manufacturing. They enable engineers to craft components with meticulous attention to detail, ensuring that the end products align perfectly with their intended dimensions and functions.

Understanding Tolerances in CNC Turning

Tolerances, in the context of CNC turning, define the allowable variations in the physical dimensions of a manufactured part. The need for tolerances arises because creating a part with absolute precision, matching the digital design to the last decimal point, is a practically unattainable feat. When digital designs undergo the transformational journey through drills, lathe machines, milling machines, and the like, a certain degree of “wiggle room” becomes necessary.

However, when you impose tight tolerances, this wiggle room shrinks significantly. In essence, tight tolerances result in parts that closely mirror the original design. Conversely, looser tolerances permit more deviation from the design, potentially affecting the part’s functionality.

The Crucial Role of Tolerances in CNC Turning

Even the tiniest deviation from desired dimensions during part manufacturing can have far-reaching consequences. Consider, for instance, a scenario where a company requires components for a high-performance engine, each precisely measuring 5 cm in diameter with a tolerance of +/- 0.01 cm. Any components produced beyond this precise range could jeopardize the engine’s performance, leading to improper fits, malfunctions, or even catastrophic system failures down the line.

Strategies for Achieving Tighter Tolerances

To achieve the coveted tight tolerances in CNC turning, engineers must consider several critical factors, including the following:

• Material Type: The material being processed plays a significant role in determining achievable tolerances.
• Complexity of Parts: More intricate parts may require additional attention to detail to maintain tight tolerances.
• Intended Functionality: Understanding how the part will function is vital in defining tolerance levels.
• Adherence to Standards: Staying compliant with industry standards is essential for precision.
• Safety Concerns: Ensuring that tolerances meet safety requirements is paramount.

Fortunately, engineers have access to various quality control tools to enhance accuracy in CNC turning. Examples include:

1. Coordinate Measuring Machine (CMM): This device measures object geometry, providing detailed analyses of dimensions to ensure products meet tolerance requirements.
2. Gauge Control: Precision tools are employed to monitor and control the output, verifying that produced parts adhere to specified tolerance limits.
3. Statistical Process Control (SPC): Utilizing statistical techniques, SPC ensures efficient process operation, resulting in improved product quality, reduced waste, and enhanced predictability in manufacturing.

Effective Communication for Tolerance Success

Achieving the desired tolerances requires seamless communication among engineers, machinists, and designers. Collaborative efforts, comprehensive drawings, and meticulous documentation are essential elements for success. Drawings enable teams to visualize specifications intuitively, encouraging the exchange of expertise and diverse viewpoints. Simultaneously, documentation processes keep everyone informed about what works and what doesn’t during component production. Effective communication is the linchpin that guides the CNC turning process, especially when tight specifications are at stake.

Tolerances: Cost Savings and Enhanced Productivity

CNC turning services not only elevate product quality but also boost productivity. Tight tolerances result in minimal material wastage. Moreover, once all components align within acceptable tolerance ranges, CNC machines can rapidly produce high volumes of parts, significantly reducing production time.

Invest in CNC Turning Services Today

At Advanced Precision Machining (APM), precision and quality are the cornerstones of our CNC turning services. We specialize in delivering industry-leading turning services, merging state-of-the-art technology with exceptional craftsmanship to produce high-quality parts. Our arsenal includes the most advanced CNC lathe machines capable of crafting components from steel, composite materials, exotic metals, aluminum, and plastics. 

This process empowers us to transform raw materials into intricate components, meeting the most stringent quality standards and exact specifications. Contact us today to learn how CNC turning services can benefit your organization.

In the world of machining, precision and consistency converge during the ingenious process of CNC turning. This computerized manufacturing method takes raw materials and sculpts them into intricate parts with highly specific dimensions. Imagine a piece of material rotating gracefully while being shaped by a computer-controlled tool; this is the essence of CNC turning.

The scope of CNC turning is wide-reaching, encompassing metals, polymers, and even wood as its materials of choice. This process is the marvel behind the intricate and complex forms that grace industries ranging from aerospace to automotive.

In this blog, we’ll delve into the world of CNC turning, exploring how it works and what it brings to modern manufacturing.

What Kinds of Components Can Be Made with a CNC Lathe?

CNC turning is exceptional at manufacturing cylindrical or elliptical pieces, but it can also yield other axially symmetrical forms. For example, cones, disks, and a plethora of other shapes can emerge during the lathe machining process.

What Happens During CNC Turning?

Creating the Initial Design

The journey from the conception of a part to its tangible reality begins with a CAD file. This blueprint acts as the guiding star for the CNC turning process, ensuring the envisioned design is accurately translated into the physical realm. Computer-guided movements will follow the digital design, creating a harmonious dance between technology and craftsmanship. 

Selecting the Right Materials

With the blueprint in hand, the next step is making a critical decision: which materials will bring the design to life? This stage is akin to choosing the canvas for a masterpiece, as the material sets the stage for the entire creation process. 

Machining shops, armed with a range of materials ranging from sturdy metals to versatile polymers, make informed choices based on the design’s demands. The experience and expertise of machinists shine as they delve into the unique properties of each material, understanding how it will interact with the CNC turning process. 

With an array of cutting tools and techniques at their disposal, these professionals meticulously prep the chosen material, ensuring it’s primed for the turning process. Tasks such as facing, chamfering, and drilling are executed with surgical precision, setting the stage for the grand transformation to come.

Sculpting the Workpiece

At the heart of CNC turning lies the art of turning itself. The workpiece takes center stage, gracefully spinning while a meticulously orchestrated choreography unfolds. During this process, the cutting tool removes material in measured increments, gradually shaping the form dictated by the digital design. 

The symphony of motions is a testament to the precision and finesse of CNC turning machines. It’s here where the magic happens, and even the most elaborate shapes emerge flawlessly, highlighting the machine’s extraordinary capabilities. 

Depending on the specifications of the part in question, the machine may complete a number of tasks, including tapering to sculpt elegant angles, threading to create intricate connections, and grooving to give components their distinct identities. The result is a workpiece transformed, a true embodiment of precision craftsmanship.

Advantages Galore: Unveiling the Benefits of the CNC Turning Process

When it comes to manufacturing incredibly precise parts, CNC turning serves as the bridge between concept and completion. Now that you have a better understanding of what happens during the process, let’s take a look at some of the biggest advantages of using it to manufacture parts.

Total Precision 

With the guidance of CAD files, CNC turning can achieve flawless precision by mitigating human error. Whether creating individual prototypes or manufacturing wholesale parts, this technology-driven process ensures every cut is intentional and, consequently, every resulting piece meets the exact specifications contained within the original design. 

Consistent Replication

Much of the magic of CNC turning lies in its ability to churn out identical products, maintaining the same level of accuracy across batches. This consistency is a linchpin in industries where uniformity is paramount.

Enhanced Productivity

Unlike manual turning, CNC lathe machining can toil ceaselessly, even overnight, boosting productivity. The machines can also juggle multiple workpieces simultaneously, accelerating the manufacturing process.

More Flexibility

CNC turning machines are available in a host of sizes, lending adaptability to diverse applications. Furthermore, a simple tweak in the CAM programming can allow operators to carry out countless modifications on the same machine, ensuring maximum flexibility when producing special parts.

Better Safety

Safety takes center stage during the CNC manufacturing process. Since automated CNC turning has little need for excessive human intervention, there is minimal risk to the personnel overseeing it. 

Faster Outcomes

When guided by programmed instructions, CNC turning minimizes errors, which can speed up production times significantly. This efficiency comes without compromising the end product’s quality.

Turn to Advanced Precision Machining for All Your CNC Turning Needs

If you need CNC turning services, look no further than Advanced Precision Machining. Our skilled machinists can breathe life into your designs with unparalleled accuracy. Let us use our state-of-the-art equipment to make your vision a reality. When you’re ready to get started, reach out on our website to request a quote for CNC turning.

From offshore drilling rigs to complex refinery machinery, the equipment used in the oil and gas industry relies heavily on well-crafted components to ensure safe and efficient operations. Consequently, the demand for durable and high-performing equipment is paramount. This necessitates a machining process that guarantees precise custom parts, which is where CNC milling services come into play.

During CNC milling, pre-programmed software dictates the movements of the production tools, yielding complex components faster and more efficiently than traditional milling. This cutting-edge technology delivers resulting parts that meet the required specifications. 

With custom CNC milling, manufacturers are able to ensure the seamless fabrication of intricate components that can withstand the most demanding environments found within the oil and gas sector. Read on to learn how this advanced technology maximizes efficiency, minimizes downtime, and contributes to the industry’s unwavering commitment to safety and reliability.

How Does CNC Milling Ensure Precise Parts for the Oil and Gas Industry?

In CNC milling, accuracy and consistency are achieved with the help of computers, which control the position and movement of the cutting tools. The saw or drill embedded within the manufacturing equipment follows the software’s instructions automatically and with machine precision, carving the source material until it meets the specific, pre-programmed dimensions. With this technology, machinists can fabricate vital components for drilling equipment, including valves, pumps, and connectors. 

Put another way, CNC milling ensures precision by using computerized processes to execute accurate movements with extremely tight tolerances based on highly specific digital designs, eliminating human error every step of the way. 

Why Is Precision Machining So Important for Equipment Used in the Oil and Gas Industry?

In the high-stakes world of oil and gas, where reliability and productivity are paramount, the importance of precision machining cannot be overstated. With the demand for efficient, durable, and custom-made equipment on the rise, many companies are turning to machine shops that offer CNC milling to meet these challenges head-on. 

Here are some of the biggest reasons why this innovative technique plays such a critical role in the current oil and gas sector:

1. Consistent Reproduction of Spare Parts

With custom CNC milling, the consistent reproduction of spare parts becomes a streamlined process. By programming unique designs into the CNC machine, manufacturers can reproduce critical components with highly specific dimensions across multiple production runs. This meticulous precision ensures that each resulting piece meets the programmed specifications precisely, leaving no room for deviation whatsoever.

In the oil and gas industry, the availability of numerous spare parts is a necessity for essential equipment. By relying on CNC milling to create exact replicas of vital components, companies can maintain an inventory of readily accessible spare parts. In the event of component wear or failure, swift replacement with an identical spare minimizes downtime and prevents malfunctions, enabling projects to maintain their momentum without any dip in productivity.

2. Impeccable Quality Assurance

As long as you turn to a reputable machine shop for your custom components, you can be sure they’ll apply rigorous quality control measures throughout the manufacturing process. Expert machinists utilize highly sensitive sensors and integrated measurement systems to provide real-time feedback throughout CNC milling operations. In the event of any deviations or issues, immediate adjustments can be made, ensuring that each part aligns perfectly with the designated specifications.

CNC milling machines boast an added advantage in their ability to conduct thorough quality inspections. As the machining process nears completion, these advanced systems verify that each component meets the highest standards possible. The commitment to impeccable quality assurance instills confidence in the reliability and performance of the finished equipment components.

3. Enhanced Efficiency and Reduced Lead Times

In the fast-paced world of oil and gas operations, time is of the essence. Downtime can result in significant financial losses and hinder project progress. Precision machining significantly enhances efficiency and reduces lead times in producing vital equipment components.

With traditional machining methods, creating intricate parts can be a time-consuming and labor-intensive process. Skilled machinists might require extended periods to craft complex designs, leading to potential delays in the supply chain. However, CNC milling streamlines the manufacturing process, minimizing manual intervention and accelerating production.

By utilizing computer-aided designs and programming, CNC milling machines execute tasks with unparalleled speed. As a result, manufacturers can meet tight deadlines and deliver critical parts to oil and gas companies promptly. This swift turnaround ensures that drilling rigs, pumps, compressors, and other machinery stay operational, contributing to seamless project execution and maximizing profitability.

4. Seamless Integration and Interchangeability

The oil and gas industry often involves extensive networks of equipment and machinery, all working in unison to achieve specific goals. For seamless integration and interchangeability, precise dimensions and standardized components are vital.

CNC milling services play a pivotal role in ensuring that every part fits precisely with others in the equipment assembly. The consistent reproduction and stringent quality control offered by CNC milling guarantee that components from different production batches can seamlessly replace one another without causing disruptions.

Moreover, CNC milling enables manufacturers to produce components with intricate features and complex geometries, allowing for tighter fits and smoother interactions between parts. This level of precision enhances the overall performance and reliability of the equipment, ultimately contributing to safer operations and more successful projects.

5. Cost-Effective with Reduced Waste

Efficient use of resources is a crucial aspect of any successful industry, and oil and gas are no exception. Custom CNC milling excels in cost-effectiveness and waste reduction, making it an economically viable choice for equipment fabrication.

Since CNC milling follows computer-programmed designs to the letter, there is minimal material wastage. Traditional machining methods often involve manual cutting and shaping, leading to a higher likelihood of errors and excess material removal. In contrast, CNC milling optimizes material usage, minimizing overall production costs.

Furthermore, the consistent reproduction and high-quality output of CNC milling reduce the need for rework or part replacements due to defects, cutting down expenses. The reliability of CNC-machined components also translates to extended equipment lifespans and reduced maintenance costs, enhancing the industry’s overall financial efficiency.

By embracing custom CNC milling for oil and gas equipment production, companies can strike a balance between top-notch quality, reduced lead times, seamless integration, and cost-effectiveness. This transformative technology empowers the industry to achieve new heights of productivity, safety, and innovation, ensuring that the global demand for energy is met with utmost reliability.

Let Us Produce Your Custom Parts for Oil and Gas Equipment

CNC milling technology has significantly improved the oil and gas industry by enabling the creation of complex, precise, and customized components for essential equipment. At Advanced Precision Machining, we specialize in custom CNC milling and take pride in delivering the highest quality parts to our clients in the oil and gas sector. Our state-of-the-art equipment and experienced team are dedicated to providing superior service, precision, and quality. Take your innovation to the next level with our CNC milling services.

If you need complex parts that can only be manufactured by CNC milling, it’s important to find the right machine shop to do the job. Before you can select a reliable and competent company with confidence, however, you must know what to look for in a machine shop. Otherwise, there’s no way to be sure your project will be in the right hands. 

Here are some of the most important considerations to keep in mind:

1. Experience and Expertise

• Years in the Industry: Choosing a machine shop with a proven track record and substantial experience is vital. Look for a company that has been operating for several years and has successfully completed projects similar to yours.
• Specialization: Determine if the shop specializes in CNC milling services. Expertise in this particular area ensures that they have the necessary skills, knowledge, and equipment to deliver high-quality results.

2. Advanced Technology and Equipment

• State-of-the-Art Machinery: Check if the CNC machine shop utilizes modern, well-maintained equipment. Advanced machinery increases efficiency, accuracy, and the ability to handle complex projects effectively.
• Diverse Capabilities: A reputable CNC machine shop should have a wide range of machining capabilities, including 3-axis, 4-axis, and 5-axis CNC milling. This ensures they can accommodate various project requirements.

3. Quality Control and Certification

• ISO Certification: Look for a CNC machine shop that is ISO 9001 certified. This certification guarantees that the company follows strict quality control processes and maintains high standards.
• Inspection and Testing: Ensure that the shop has robust quality control measures in place. This includes thorough inspection and testing procedures to verify the accuracy and precision of the machined parts.

4. Material Selection and Sourcing

• Material Expertise: Different materials require specific machining techniques. A reliable CNC machine shop should have expertise in working with a wide range of materials, including metals, plastics, composites, and more.
• Material Sourcing: Inquire about their material sourcing capabilities. A reputable shop will have established relationships with trusted suppliers to ensure the availability and quality of materials for your projects.

5. Customization and Flexibility

• Customization Options: Discuss your project requirements with the CNC machine shop and ensure they can accommodate any customization needs. The ability to adapt and tailor their processes to your unique specifications is crucial.
• Quick Turnaround Time: Timeliness is essential in today’s fast-paced manufacturing industry. Choose a CNC machine shop that can deliver projects within your desired time frame without compromising quality.

6. Customer Reviews and References

• Online Reviews: Research online to read customer reviews and ratings about the CNC machine shop. Pay attention to feedback regarding their professionalism, communication, adherence to deadlines, and overall satisfaction.
• Request References: Don’t hesitate to ask the CNC machine shop for references from their past clients. Contact these references to gain insights into their experience working with the shop

Selecting the right CNC machine shop is a critical decision that directly impacts the success of your manufacturing projects. By considering factors such as experience, advanced technology, quality control, material selection, customization options, and customer reviews, you can make an informed choice. Remember, finding a reliable CNC machine shop that aligns with your requirements will ensure top-notch CNC milling results and a fruitful collaboration.

About APM

Advanced Precision Machining provides a wide range of CNC milling services. Founded in 2005, we have earned our reputation as the leading machine shop in Colorado because of our cutting-edge technology, meticulous attention to detail, and exceptional customer service. To discuss your manufacturing needs, reach out today.

Computer numerical control (CNC) milling uses software-guided machinery to create precise parts, many of which have intricate or complex features. Because this process is so accurate, it can be used to produce parts that are needed for high-stakes applications. In the medical field, for example, CNC milling is used to create customized medical devices, prosthetics, and surgical instruments. 

This technology has revolutionized the healthcare industry by providing a more efficient way to yield even the most complicated devices. It also reduces production time and increases patient satisfaction.

Because they’re so versatile, CNC milling services are in high demand. The industry was worth over $14.6 billion in the United States in 2018 and is expected to reach almost 23 billion in 2026. A significant portion of this increase will undoubtedly be attributed to its applications in the medical field. 

Let’s take a look at some of the most common medical parts that are produced by CNC milling:

Custom Implants

CNC milling can create implants that are specifically designed to fit the patient’s unique anatomy. Such implants are preferable to the standard “one-size-fits-all” devices, since even a small deviation from average can hinder healing and cause ongoing issues like chronic pain.

Custom implants are most often used to address medical conditions like bone cancer and severe arthritis. Because they yield better patient outcomes and cause fewer complications, though, they’re gradually becoming the norm in all kinds of other scenarios.

Dental Restorations

Since it’s such a precise technology, CNC milling can be used to create dental restorations such as crowns, bridges, and veneers. With the help of specialized software, this process ensures that every restoration is made with the highest level of accuracy, resulting in a perfect fit for the patient. It’s primarily used to produce dental restorations made from ceramic, metal, or composite resin.

Prosthetics

Patients who have lost their limbs to injury or illness can get incredible prosthetics thanks to CNC milling. To enable the creation of prosthetics, body scans are digitized and then used to build an identical 3D model on a software platform. The model is then used in the creation of the blueprint for the replacement limb.
Prosthetics were traditionally created manually, which left considerable room for error. With CNC milling technology, though, prosthetics can be made with the highest level of accuracy, resulting in a perfect fit and better quality of life for the patient.

Surgical Instruments

Scalpels, forceps, and other tools used in surgical procedures are now made with CNC milling. These machines can produce instruments with intricate details and features that are difficult to achieve via traditional manufacturing methods. As an added benefit, these computer-automated machines have no quantity restrictions. That means they can meet the demand for both low-volume individualized surgical instruments and massive numbers of identical precision components.

Let Us Produce Your Custom Medical Devices

CNC milling technology has significantly improved the medical industry by enabling the creation of complex, precise, and customized medical devices such as implants, prosthetics, dental restorations, and surgical instruments.
At Advanced Precision Machining, we specialize in custom CNC milling and take pride in delivering the highest quality products to our clients in the medical industry. Our state-of-the-art equipment and experienced team are dedicated to providing superior service, precision, and quality. Take your medical device innovation to the next level with our CNC milling services.

In our tireless and dedicated effort to manufacture high-quality precision parts, and maintain a reputation for accuracy and on-time reliability, Advanced Precision Machining (APM) Colorado machine shop relies on an assortment of Computer Numerical Control (CNC) machines in our facility. In today’s modern machine shop, CNC equipment typically consists of multi-axis milling machines, lathes, routers and grinders, but also newer technology such as robotic welders, laser marking machines, and 3D printers. With origins dating back to the 1950s, what was known first simply as “numerical control” lessened the need for constant operator attention and took the machine tools out of the hand of machinists, allowing for a first of its kind automation. Today, the punch tapes associated with numerical control have given rise to advanced computing technology, programming languages and computer-aided design (CAD) capabilities, making CNC technology an integral part of most manufacturing processes.

At its core, CNC involves the use of computers to control the various machine tools listed in the first paragraph, and they function through the use of numerically controlled computer programs, most often written in a CNC machining programming language called G-Code. G-code sends the signals, or directions, to a piece of machining equipment on the shop floor directing such essential functions as cutting tool speeds, spindle position, feed rates, and all other coordinated movements. Most modern CNC systems have become highly automated and quite complex, augmented by the addition of CAD and computer-aided manufacturing (CAM) programs. Due to the complexities involved with modern machining, CNC machinists have evolved to become skilled in all aspects of drawing and design, code writing, and equipment operation. When all’s said and done however, a precision machined part in the end is only going to be manufactured as well as the programming that was input to create it. Because of its importance, APM would like to provide a short primer on some common CNC programming methods.

As stated, CNC milling machines require a set of precise programming instructions to control nearly every aspect of the milling and machining process. After a CAD drawing is first drafted, the actual programming code (G-code) is created in a language that the CNC machine will understand. The program is then loaded into the microcomputer, or controller unit directly on the machine where it is stored in memory, then tested for accuracy. A CNC machinist next loads the required tools and material, then the computer directs the machine to perform the cutting operations according to the programmed instructions. Given the critical nature of CNC programming, let’s briefly examine three of the most commonly used methods: manual, conversational and CAM programming. 

1.  Manual (non-conversational) CNC Programming

Perhaps thought of as the purest method, manual programming involves a CNC machinist preparing G-code commands without the assistance of a computer, thereby manually giving the CNC machine instructions on where to move, how fast, and on what path. Also known as non-conversational, it allows for complete control over a part program. This intimacy between programmer and machine brings out better machine performance when compared to more automated computerized methods. Because it’s done by hand, manual programming teaches strong discipline and is ideal for simple or high-volume work, although it’s time consuming and runs the risk of human error.

2. Conversational (shop floor) CNC Programming

Conversational, or shop floor programming involves creating a set of programming instructions directly at the CNC machine using displays and menu-driven functions. The need to manually create G-code is either hidden or bypassed entirely, allowing a CNC machinist to step up to a machine and generate a CNC program quickly and easily. The program takes over and puts the machine in motion according to the commands given. It’s easy to learn and simple to use for small lots and short cycle times, but limited to more basic machine parts without complex tool paths.

3.  Computer-aided Manufacturing (CAM system) CNC Programming

A computer-aided manufacturing system combines elements of both manual and conversational CNC programming by computer generating the G-code written in manual programming, then directly and automatically transferring it to the machine tool. The dimensions specific to a workpiece’s design are imported from a CAD system, the machinist directs the machining commands through a menu, the G-code program is generated, loaded into the machine, then it is left to run. Although it automates many processes and improves output, the total machine control associated with manual programming is limited. 

The description and methods shown for developing the CNC programs all have developed their own specific niche in the precision machining industry. They of course have a comprehensive list of additional pros and cons surrounding their use, and as any CNC machinist can tell you, their preferred use comes down not only to specific machining needs, but also personal preference. Be sure your machine shop chooses the optimal CNC programming method to deliver your parts accurately, on time and on-budget.

Need help with your next project requiring the precision and accuracy delivered by CNC, or want to learn more about the range of precision milling and machining options available to you, then contact our Colorado CNC machine shop. Advanced Precision Machining’s reputation for quality parts, on-time reliability and exceptional customer service cannot be matched! We’re happy to discuss any machining needs you have. Feel free to give us a call at 303.776.1910

For more APM machine shop information; Like us on Facebook, follow us on Twitter @APMLongmont, or connect with us on LinkedIn.

About the Author

Gerry Dillon is a co-founder, current owner and certified CNC machinist at Advanced Precision Machining (APM), a full-service machine shop located in Longmont, Colorado. Before making his home in the United States in 2000, Gerry was born and raised in Ireland and took an interest in milling and machining from an early age, ranking #1 in the Irish National Apprenticeship Program. In 2005, he began what’s grown into a leading Colorado machine shop. Gerry brings over 30 years of machining experience to the shop floor, and is certified in all aspects of geometric dimensioning and tolerancing.

To an outsider unfamiliar with CNC machine shop operations, once the chips stop flying, the milling machine winds down and another precision machine part rolls out, they may well think the end product is accurate and up to specification. Unfortunately, this is not always the case. At Advanced Precision Machining, and any CNC shop for that matter, no finished part is delivered to a customer until it passes an inspection reporting process. A part’s dimensions must conform to the tolerances set in place for its design, and this includes thoroughly inspecting the finishes of all machined surfaces. As is often the case, a part may meet specific dimensional specifications, but must be scrapped because its overall appearance and surface finish is not up to standards. This not only results in an aesthetic issue, but more importantly, can negatively impact a part’s functionality.

The bottom line is that during the finishing stages of the milling and machining process, having to send parts to the scrap bin is less than a desirable outcome. CNC machinists by nature are detail-oriented, take great pride in their work and want to see a project through to completion. Scrapping parts as a result of surface finish issues can also be a real profit killer for machine shops. Poor quality leads to increased costs, more downtime, delayed deliveries, and in the worst case scenario, lost orders. The question becomes; how do machinists and shops address this issue? What can be done when the end results aren’t up to par? Let’s take a quick look at just a few simple tips and tricks on how to get the best surface finish possible using a CNC milling machine. Bear in mind that this is only the tip of the iceberg! 

1. Increasing cutting tool speed

Faster velocities, measured in surface feet per minute (SFM) mean material is in contact with the cutting tool for less time. This works to reduce edge buildup resulting in poor surface finishes, and also extends the life of the cutting tool. Tool failure is a leading cause of damage to a precision machined part. Never estimate or guess at the required speeds for your job. 

2. Always clear away/control chips

Clearing excess chips, or built up edge (BUE), and not allowing them to contact the workpiece during machining operations is a vital task and key to producing a high-quality surface finish. Chips and BUE have a tendency to build up, and if not cleared, can easily damage surface finishes as the cutting tool makes contact with them. Chip breakers, compressed air, and the best solution, flood coolant can be used to clear away chips and BUE for better control and less scratching/damage to parts.

3. Different tools should be used for roughing vs. finishing applications

Don’t finish a part with the same tool used for roughing. Instead, slightly used roughing tools should be utilized for the bulk of material removal, while brand new, sharper tools should be saved and only used for finishing passes. Tooling insert radius, rake angle, feed rates and insert material itself, when combined with roughing vs. finishing tools can lead to a higher quality finish.

To the layperson, simply examining a precision machined part for its aesthetic appearance may seem all that’s necessary once milling and machining has ended and delivery is near. Thoroughly inspecting completed work, regardless of material, is instead a critical factor for a part’s functionality; especially for applications in industries such as aerospace and medical device manufacturing. Excess chips and/or BUE, slow operating speeds, and improper tool use are leading causes of poor surface finishes. Lack of machine maintenance, low levels of cooling fluids, poor setups, and CNC programming errors are also contributing factors. The tips we’ve provided are applicable across a variety of machine shop operations, including milling, turning and grinding, and if adhered to, should go a long way to improving the surface finishes on your problem jobs, resulting in satisfied customers and repeat business.

Do you have questions? Want to learn more about surface finishing applications? APM’s Colorado machine shop is available for all of your inquiries. We’re dedicated to manufacturing the highest quality precision parts while providing the best customer service experience in the machine shop business. For additional information or to request a quote, please visit https://advancedprecisionmachine.com or call 303-776-1910.

For more APM machine shop information; Like us on Facebook, follow us on Twitter @APMLongmont, or connect with us on LinkedIn.

About the Author

Gerry Dillon is a co-founder, current owner and certified CNC machinist at Advanced Precision Machining (APM), a full-service machine shop located in Longmont, Colorado. Before making his home in the United States in 2000, Gerry was born and raised in Ireland and took an interest in milling and machining from an early age, ranking #1 in the Irish National Apprenticeship Program. In 2005, he began what’s grown into a leading Colorado machine shop. Gerry brings over 30 years of machining experience to the shop floor, and is certified in all aspects of geometric dimensioning and tolerancing.

With the holidays rapidly approaching, the ownership and entire team of professional CNC machinists at Advanced Precision Machining (APM) want to wish everyone seasons greetings and best wishes for a Happy New Year. We’d also like to thank our customers for their continued support and loyalty. The milling and machining business has remained productive for us, and the hard work of our employees has grown APM into one of the Front Range’s premier machine shop operations. Part of this work is dedicated to education and keeping our customers informed with regards to the many milling and machining techniques used in our sector of the precision manufacturing industry. So, as we reflect upon another successful year of operations and look forward to 2023, we want to take this opportunity to revisit what may appear on the surface to be a seemingly simple procedure we offer as part of our CNC turning services; the various methods utilized for generating screw threads. 

When looking at the simple threads on any screw, to the layperson, it might seem as if the machining techniques used in the manufacturing processes are among the least complicated on the machine shop floor. But in reality, due to generally higher cutting forces and tight tolerances, machining screws (aka thread turning), is significantly more challenging. When you factor in the additional demands required of micro-threading, utilized in products such as watches, eyeglasses, cell phones, and medical devices, you’ve upped the workload substantially. Herein lies the difficulties many shops face. From one-off specialty items, to mass-quantity production runs, more screw threads are produced in a given year than any other CNC machining element. 

While threading is used across many varying industries and takes on many roles, from the large scale down to almost micro levels for custom precision machining projects, every type of thread is ultimately machined to provide specific functions for specific applications. The processes involved in creating a screw thread are varied, encompassing a wide range of subtractive machining, deformative, transformative, and even additive methods. Today’s revolution in modern machine shop technology means precise and accurate screw threads can be produced more quickly, accurately, and efficiently regardless of size. What follows below is a brief look at the most common technique; the subtractive method of cutting screw threads.

Bearing in mind that thread turning involves both external and internal threads, with the latter being more demanding, choosing an appropriate application for machining screw threads is based upon the constraints of time, money, equipment, and the degree of precision needed. Subtractive CNC machining methods involve the removal of raw material from a blank, and are universally accepted as the most efficient, cost effective, and least complex methods to choose from. These include: Thread Cutting, Thread Grinding, and Thread Lapping techniques.

Thread Cutting (Tap and Die, Single Point, and Thread Milling Processes)

Tap and Die Method

• Metal screw threading using taps and dies goes back to the eighteenth century. A tap is designed to thread the inside, or female surface of a hole, such as a nut. This can be done manually using various tap wrenches, or power assisted with a CNC lathe or high speed milling machine. Dies form mates for tapped components by threading the outside, or male surface, of a metal cylinder such as a bolt. Again, this can be done with hand devices, or with CNC machining tools.

Single Point Threading Method

• Single-point threading is less common, and uses a single-point tool on a CNC lathe to impart a thread on the inside or outside of a rotating part. Single-point threading is favored over tap and die, or other methods, but only when certain manufacturing factors dictate it.

Thread Milling Method

• Thread milling is a more accurate CNC milling operation in which a rotating multi-point tool threads the surface of a workpiece if a helical toolpath can be maintained. It’s a useful alternative to standard methods for producing threads with good form, finish, and dimensional accuracy. Faster work, less breakage, and left or right-handed threads can be machined using the same tool.

Thread Grinding

The precision manufacturing of screw threads can also be performed on a variety of grinding machines utilizing specialized wheels accurately profiled to the desired thread pattern that traverse along the revolving workpiece. Thread grinding is typically used to produce threads to very exacting tolerances, or in extremely hard materials. The most common machine, the universal type, specializes in threading gages, screws, plugs, rings, hobs, and even other threading tools such as taps and dies.

Thread Lapping

• Lapping a screw thread involves a process of abrasion in which threads are finely finished on a workpiece by successively traversing, or lapping the workpiece as it revolves. Lapping helps achieve the highest precision and surface finish available, and is normally performed after thread grinding. Two surfaces are typically moved together via a machine with the abrasive material between them, producing the desired result.

Although the subtractive techniques involved in machining screw threads described above garner the most attention on the machine shop floor and are most commonly employed there, deformative or transformative methods, and even additive (3D printing techniques) warrant mentioning. Thread forming, for creating internal threads, and thread rolling, for creating external threads, both involve deforming or transforming the metal used to manufacture screw threads. In short, the threads are formed by pressing a shaped tool into a metal blank, commonly called a ‘thread rolling die’. Used in large production runs due to their efficiency, thread rolling/forming dies have the capability to produce one new piece per second and produce none of the waste, or swarf, that’s associated with subtractive methods. Additive manufacturing utilizing 3D printers is gaining increased potential for creating threaded parts, but the technology is not quite where it needs to be just yet. The good news is that further commercialization is on the horizon, and the industry is making some inroads into the dental implant and medical bone screw fields.

Need help with your next threading project, or want to learn more about the range of precision machining options available to you, then contact the CNC machine shop and thread generating experts at APM. Our reputation for quality parts, on-time reliability and exceptional customer service cannot be matched! We’re happy to discuss any machining needs you have. Call us at 303.776.1910 or send us an email.

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About the Author

Gerry Dillon is a co-founder, current owner and certified CNC machinist at Advanced Precision Machining (APM), a full-service machine shop located in Longmont, Colorado. Before making his home in the United States in 2000, Gerry was born and raised in Ireland and took an interest in milling and machining from an early age, ranking #1 in the Irish National Apprenticeship Program. In 2005, he began what’s grown into a leading Colorado machine shop. Gerry brings over 30 years of machining experience to the shop floor, and is certified in all aspects of geometric dimensioning and tolerancing.