What Is CNC Machining?
Many components for the medical device industry are manufactured using CNC machinery. A CNC machine or “CNC machine tool,” is a computerized, numerically controlled machine that is used to remove material though various forms of cutting, including milling, turning, drilling, and grinding. Each form of cutting is a pathway to the completion of a part.
How Does CNC Machining Work?
Using CAM (computer-aided manufacturing) software, CNC machine tools are programmed to navigate to different positions along specific pathways at different patterns and rates of speed. In combination with different types of cutting tools, CNC machinery can be configured to accommodate a specific product or a wide variety of applications.
See CNC in Action
This comprehensive discussion provides an overview of CNC machining.
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History of CNC Machining
at Hobson & Motzer
- CNC milling
- CNC turning
- Indexed
- Continuous
- Hybrid—Milling & Turning Combined
Fully Automated for Excellence
- Investment in Technology
- The Importance of Metrology
History of CNC Machining at Hobson & Motzer
Hobson & Motzer began in 1912 as a metal stamping manufacturer. Over the years, innovative new materials and technologies, capabilities, and manufacturing processes were added to the portfolio. The company built upon its metal stamping expertise to incorporate CNC machining more than 20 years ago—along with several post-processing operations, such as finishing, deburring, laser welding and marking, and surface printing for identification.
Hobson & Motzer excels in manufacturing products that require more than a single operation or products that require multiple
manufacturing processes. Our forward-thinking philosophy has enabled us to create the impossible—often pushing the limits of what clients have been told is not possible by other companies.
The ability to “answer the call,” to respond to our clients’ evolving needs, is baked into the pedigree of Hobson & Motzer. At each stage in our development, we have learned, embraced, and mastered new technologies and techniques. Today, CNC machining is integral to the majority of the components produced, many fully machined, and many stamped parts with machined features.
Our team brings a 360-degree perspective, from across all disciplines, into the inception, design, and production phases of manufacturing. As your manufacturing partner, we are strong, nimble, adaptive, and highly effective. Our advanced manufacturing technologies—and dedicated workforce and laser focus on quality—result in achieving precisely controlled processes and exceptionally high tolerances for our medical device and instrumentation clients. We continually seek to enhance, streamline, and innovate each step along the CNC machining process for truly exceptional outcomes.
Types of CNC Machines
Hobson & Motzer has some of the most precise vertical CNC machines available: 80+ machining centers with 3-, 4-, and full 5-axis capability. Our expertise in machined components is complemented by a team of expert applications engineers with diverse backgrounds in the medical device, aerospace, automotive, and mold-making industries.
Our equipment is high-end, robust, production-ready, and versatile. Our diversity provides great flexibility to apply the most suitable technology for your application. For high-volume applications, our in-house team designs and builds state-of-the-art robotic-controlled automated systems for maximum efficiency.
3-Axis
CNC Milling
The most basic and economical of the milling options, 3-axis CNC milling allows for simple movement of the cutting tool—left to right, up and down, and back and forth, also known as X, Y, and Z axes. This approach is good for parts with simple geometries and best for applications requiring linear movements. Three-axis machining allows for 2D and 2.5D geometry to be used while milling a fixture. This process is a gateway into CNC machining; the linear axes are the base layer for all other axes.
CNC Turning
CNC lathes do not rotate, instead, moving radially and lengthwise. In this instance, material is locked on a rotating spindle while the mounted tool works to remove specified material to arrive at a finished product. This technique works well for higher volume parts that need to be produced at a lower cost per unit. Because CNC lathes cannot produce cylindrical-shaped parts, some parts may need to be machined using a separate process.
Multi-Axis Machinery
Multi-axis machinery is a term that encompasses any CNC machinery from 4-axis to 9-axis milling. This means that a CNC machine that can operate in the three linear axes, and at least one additional axis can be labeled as a multi-axis machine. Upgrading to multi-axis machining offers numerous benefits. Fixture set up times are greatly decreased, as multi-axis machinery can reach more than one side of the fixture within a run. When a fixture can complete a multi-axis cycle, the tolerances of the program are greatly improved as compared to non-multi-axis machining.
Indexed 4-Axis Milling
With indexed 4-axis CNC milling, the user can access all linear directs while also being able to use a rotational axis, usually the A-axis. This additional usage of a rotational axis will allow for more complex geometries, a step up for 2 and 2.5D geometries. An indexed 4-axis milling process will allow for four sides of a part to be machined within the same fixture set-up, which greatly increases time efficiency.
Continuous 4-Axis Milling
Continuous 4-axis CNC milling involves access to all three of the linear axes, X, Y, and Z—along with the use of a rotational axis, usually the A-axis. As compared to indexing, continuous 4-axis milling allows for constant movement of the rotational axis throughout the entire machining process. Continuous milling benefits the user by creating more intricate contours along the part. Continuous 4-axis milling eliminates down time due to fixture set-up, even more so than indexing.
Indexed 5-Axis Milling
Indexed 5-axis CNC milling, also known as 3+2 axis milling, allows for more complex geometries to be manufactured, as they add two additional degrees of flexibility. This means that while the three linear axes—X, Y, and Z—are being used, you also have the option of two rotational axes, A or B and C. The workpiece does not need to be repositioned manually, so greater efficiencies can be achieved.
Indexed milling is ideal for applications that require the unlocking of different sets of features at different angular positions. Indexed 5-axis milling allows for the reduction of the total number of operations needed to produce a given product or part.
Continuous 5-Axis Milling
Continuous 5-axis CNC milling systems allow a great deal of flexibility, as all five axes can move at the same time during machining operations, meaning the machine can maintain an infinite number of axes combinations, unlike indexed 5-axis milling. Continuous 5-axis milling uses the linear X, Y, and Z axes, while simultaneously using two rotational axes, A or B and C.
These advanced capabilities allow for the production of complex geometries and more organic forms, while delivering precision and high tolerances. This milling approach works well for optimizing a CNC production process. Continuous 5-axis milling is considered the quickest option for milling a part, due to reduced downtime.
Hybrid—Milling & Turning Combined
CNC lathe machines are equipped with CNC milling tools to offer the best of both worlds—the flexibility of milling and the high productivity of turning. The workpiece can be positioned to either rotate at a high speed or placed at an angle. Mill-turning works well for manufacturing parts that require loose rotational symmetry at a lower cost than other 5-axis CNC machining systems, and often offer a reduction in the number of operations required to produce a part.
Benefits and Limitations of CNC
Benefits
Small to Medium Production
CNC machining makes sense for small to medium product volumes, typically within a broad production range. The set-up costs for a CNC manufacturing operation are quickly offset by the economies of scale achieved when producing multiples of identical parts. Of course, the production of large quantities of the same parts will also allow for well-balanced standardization on top of the decrease in production
costs.
One of the chief advantages of CNC-machined parts is their superior physical properties. When tight tolerances and high performance are critical, CNC machining allows for design flexibility and choice of materials. CNC machining doesn’t require any special tooling, making on-demand production of prototypes and parts easily attainable and affordable.
Hobson & Motzer’s investment in CNC systems, automation, and digital supply chains have greatly accelerated production times. We can now deliver quality CNC-machined parts at faster speeds, while continually improving our processes in real time, anticipating current and future needs.
Limitations
While CNC machining offers many design, scale, and economic benefits, there are some limitations. Start-up costs—which require the manual input of data—can be relatively high, but as fixed costs, can be offset by higher production runs. Complex geometries can increase the cost of a part, and limitations of the geometry of cutting tools may also place limitations on how a part is designed.
First Step Program
Designing for leading OEMs in the medical device sector requires staying ahead of the curve to help you successfully develop and introduce exciting new products. Hobson & Motzer launched First
Step in 2020 to meet the demand for higher level rapid prototyping, executed to precise tolerances.
An important hallmark in product development from a manufacturing standpoint is that from the beginning, the components must be assessed for their entire lifecycle. A project-based approach builds long-term stability into the process from the very first step. Our rapid precision prototyping allows the part and manufacturing process to evolve simultaneously, yielding valuable data and learning that does
not occur when the two processes are separate.
Beginning with an insightful DFM exchange early in the process can steer the manufacturing costs of an initial design in the right direction. The process should include supplier input from process and materials engineering and quality control. This important step allows any issues to be identified and addressed up front, saving time and money.
First Step employs the same proven processes that are applied in large-scale production programs from the get-go—with the full force of our team and talent behind it. We add significant value to your process, optimizing your NPI/NPD components from every angle, and helping you get to market faster.
Our collaborative First Step precision prototyping provides:
- Precision tolerance prototyping
- Inspection strength, state-of-the-art metrology
- Robust DFM expertise and access to a
solid manufacturing support team - Efficient proof of concept
- A nimble, resourceful infrastructure
- Fast turnaround and long-term manufacturing efficiency
- Reliable fit, form, and function at the component level
Fully Automated for Excellence
Investment in Technology
Hobson & Motzer’s ability to excel and innovate requires the best technology. The company’s extensive investment in the most advanced equipment and technologies available drives advanced designs that propel advanced achievements in the medical device and instrumentation industry.
Each of our machining centers is fully networked for systemic performance monitoring for overall equipment effectiveness (OEE)—helping to mitigate downtime and changeovers and optimize quality data and preventative maintenance scheduling. Each unit has modern controls, allowing us to run production consistently and safely at maximum speeds with minimum downtime.
Our deep resources—80+ CNC machining centers, advanced software, high-end metrology, and inspection systems; and ability to build our own tooling, program our own jobs, document our processes, and control our systems—ensure that we help our customers deliver the next generation of innovative medical devices and instrumentation.
Our equipment is matched with exceptional programming talent. Hobson & Motzer’s highly skilled application engineers are well versed in the latest approaches. Our apprenticeship and training programs help to ensure legacy knowledge is shared among our deep bench of dedicated staff.
Multiple considerations contribute to the technical precision of a CNC-machined part. Our programmers are highly knowledgeable about the different properties of a wide variety of materials. They understand how materials react to their own built-up stresses, and how they move and relieve when specific amounts are removed.
Vibration also plays a critical role in CNC machining. Our programmers’ extensive experience in which tools to use, and how much material to remove to minimize or control vibration, is central to the precision of the final product. How a part is processed is also important. CNC programmers look at a variety of factors, from how a part is held while it is being machined, to the types of cutting tools to be used, to what parameters are applied.
The Importance of Metrology
Metrology, within the manufacturing realm, is the science behind perfecting each produced part to the precise size and shape required within specified tolerances. The tighter the tolerance machined out using CNC machining, the more you will want to rely on metrology.
Metrology is vital because it fuels the constant process of communicating part quality through all stages of the manufacturing of parts. State-of-the-art metrology enables us to perfect our parts, adhering consistently and continuously to detailed guidelines and client specifications.
Hobson & Motzer has a vast array of measuring equipment—from hand-held instruments, such as micrometers and calipers, toolmakers microscopes, and comparators—to complex probing CMMs and Vision CMMs, as well as conventional instrumentation.
Using each piece of measuring equipment, data can be used to verify conformance, inform for improvements, and have a better understanding of the fit, form, and function of parts manufactured. For example, in one instance, measurement probes were used to gauge the accuracy of each cut that was made on a part. These probes relayed the exact measurements of the milled material.
Both attribute and variable data are used to drive part disposition. Attribute data is a quicker, easier way to verify larger tolerances and can sometimes simulate function, while variable data can be a more precise way to measure to a greater discrimination than customer requirements.
Employing the latest inspection technologies allows Hobson & Motzer to better realize your intended design. With the ability to measure parts in 3-D, using both probe and vision CMMs, we can create profiles, flatness, or other geometry comparisons. These systems also export data automatically to track data, make changes, and visualize the reaction of the changes.
We understand that every part we produce reflects on who we are as a company. Our commitment to continual improvement within the field of metrology helps assure our ability to manufacture reliably precise, well-built parts consistently.
CNC Technology Advances Med Tech Innovation
CNC machining technology is uniquely suited for the medical device market. The amazing advancements in medical devices, minimally invasive instruments, and robotic surgery have paralleled Hobson & Motzer’s evolution as an exceptional manufacturer of precision metal components.
We share a vision with our industry-leading med tech partners: design without the constraints of how, or even if, a component can be made.
Technology follows innovation and sometimes innovation follows technology—it is a symbiotic relationship. Manufacturing the components for such devices and instruments requires a diverse
skillset and vast understanding of the machines and the metals from which they are made.
Our next-gen projects begin at the earliest stage through our First Step program. Hobson & Motzer brings a deep level of expertise and meaningful DFM. We nurture the entire design process, rather than thinking about DFM almost as an afterthought, saving time and resources.
Our robust CNC machining capability and advanced metrology and inspection systems support the overall success of our medical device parts and components manufacturing. We maintain control over the manufacturing process with post-production operations that include finishing, deburring, laser welding and marking, surface printing for identification, specific coatings, and an assortment of in-house developed processes particular to the product itself.
Legacy knowledge, a deeply collaborative approach—internally and with customers—along with our vertically-integrated secondary operations, give customers access to a complete suite of services and capabilities, exceptional support, and over 100 years of manufacturing expertise.
Other Precision Metal Manufacturing Processes
For high-precision parts with complex geometries, CNC machining is often the only production method capable of meeting specifications. This is especially true for many of the components used in expanding robotic surgery platforms. Today’s CNC technology can produce critical features with higher precision and tighter tolerances, especially helpful at the prototype stage.
There are some applications for which CNC machining is not the right choice. For applications that require a very quick turnaround time, have complex geometry, or have irregular quantity demands, 3D printing may be appropriate. For very high volumes (1,000+), forming technologies such as injection molding or investment casing are better suited. CNC machining works best for the creation of high-end products with strict tolerances, with the average tolerance being 0.02mm.
There are many different technologies available to produce a product, and Hobson & Motzer can help you identify the best method for creating your part.
Material
Hobson & Motzer can help you select the right material and grade for your application.
The graphic below offers a quick visual of what metals help meet your requirements. Of course, we will work with you to choose the best material for your project.
Material Property
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If you have more questions and are interested in a successful collaboration for your next precision manufacturing need, contact Hobson & Motzer now. We’d love to discuss how we can help.
