How Better Workholding Cuts Hidden Costs and Boosts Spindle Uptime

Workholding systems that rely on the operator to perform all steps of the setup process inherently fosters variability and delays. Each setup is a one-off process dependent on each operator’s skill level. This not only increases setup time, but makes it difficult to train operators and achieve a consistent setup across multiple shifts and different machines.

Selecting the correct workholding solution can ease this burden. In particular, zero-point workholding systems offer high repeatability and standardize the top tooling mounting interface. Choosing a workholding system that offers standard setup-reducing features, such as quick-change jaws and precision ground locating features for machine tool probing, will further simplify the process and allow setups to be installed and removed without re-indicating. Once a zero-point system is installed, it becomes a repeatable and reliable foundation for all future setups. The result is simple: more time cutting chips and less time setting up.

Improved process stability and part quality

When dimensions drift or it becomes difficult to hold a required surface finish, it’s common to blame the cutting tool or the machine tool, which leads the operator to slow down speeds and feeds or increase inspection frequency. In many cases, however, the instability originated from the workholding.

When the workpiece is not held securely, small movements and vibrations affect how a cutting tool engages the material and how it moves through the material. This directly impacts your ability to achieve tight tolerances and smooth surface finishes. Any inconsistency in the workholding is amplified through the cutting tool and ultimately affects the workpiece quality.

Utilizing a workholding system that incorporates self-centering vises with high clamping force to minimize jaw lift will reduce variability, increase process stability and improve workpiece quality. Self-centering vises reduce the need for constant offsets by keeping the workpiece centerline in the same position despite variations in saw-cut blanks or different workpiece lengths. Maximizing clamping force minimizes workpiece movement and vibration. Reducing jaw lift and part lift maintains process stability and minimizes lost clamping force to jaw deflection. A stable and dependable machining process also reduces cycle time and inspection frequency.

Better cutting tool performance and life

Cutting tool performance is closely tied to the stability of the machining process. When the workpiece is not held rigidly, vibration and chatter will occur at the cutting interface. This leads to uneven cutting tool wear, reduced cutting tool life and, in some cases, premature cutting tool failure. This is particularly important with the recent spike in carbide costs and the subsequent increase in cutting tool prices.

When considering workholding solutions, maximizing holding force and improving cutting tool access are critical to maximizing cutting tool life. To achieve maximum cutting tool access, it’s beneficial to use a modular workholding system. This will allow you to quickly and easily match your workholding. Improved cutting tool access means shorter, more rigid cutting tools, a reduction in chatter and vibration, improved surface finishes and extended cutting tool life. Improved holding force and cutting tool access reduce cutting tool cost and process variability.

Increased operator confidence

Operator involvement is rarely noticed, but it is an impactful hidden cost associated with workholding. When the workholding setup is inconsistent or unreliable, the operator will often stay close to the machine, sometimes with their hand over the emergency stop button, instead of starting work on the next machine or performing other tasks. This hidden cost presents itself as poor labor utilization, increased overtime and scheduling delays. The machinist often takes the blame rather than the true root cause, leading to poor morale and increased turnover, further exacerbating labor shortages.

A reliable workholding solution with high accuracy, repeatability and holding force will reduce this dependency. Operators should feel confident walking away from the machine after pressing cycle start so they can take care of their other responsibilities. Consistent clamping force, predictable part location and repeatable mounting produce a workholding setup that allows your CNC machines to run unobserved during the machining process.

Workholding is the process foundation

A more effective way to evaluate workholding is to view it as the foundation of your CNC machining operations, rather than a standalone component. Workholding connects the machine tool, the cutting tool and the workpiece. It determines how the part is located, how it withstands cutting forces, and how consistently a part can be machined. For operators, workholding impacts the speed with which they can transition between parts, the level of confidence they feel when running parts, and the ultimate workpiece quality they produced.

When workholding is optimized as the foundation of the CNC machining process, setup becomes faster, easier to train, and more consistent. Cutting chips becomes more stable, cutting tool performance improves, and operators gain confidence in the process. From an organizational perspective, this approach aligns workholding performance with the broader process and efficiency goals of the entire organization.

Improving the entire machining process

Hidden machining costs often result from small inefficiencies that accumulate over time. Workholding often plays a significant role in many of the inefficiencies, even though it is rarely identified as the source. Improving workholding directly reduces setup time, improves repeatability, extends cutting tool life, increases cutting tool access, and increases operator confidence. The result is higher machine tool utilization, improved part quality and improved labor productivity.

In manufacturing environments where productivity and consistency are critical to success, workholding should be evaluated not just for its ability to hold a part, but also for its ability to support and improve the entire machining process.

about the author: Austin Heisick, workholding global product manager at Mate Precision Technologies, has more than a decade of experience in manufacturing, application engineering and process improvement within the metal cutting industry. He can be reached at austin.heisick@mate.com.