Category: Innovative Machining Approaches

In previous generations, machinists had to look at readouts on tables and manually lay out plans before going to work on a part. But exciting advancements in computerized numerical control (CNC) technology have made machining far more predictable, repeatable and efficient. In the modern era, builders can gain an advantage by choosing a manufacturing partner on the cutting edge of CNC machining technology.

CNC: Machining in the Modern World

Today's CNC equipment allows for a level of motion control that simply cannot be achieved with conventional methods and equipment. As long as the part is clamped in the right position, operators can use a predefined software program to "command" their equipment to mill and drill various shapes over and over again exactly the same way.

This level of predictability and repeatability has opened doors to unattended machining — the process is so reliable that operators can set the program, walk away and do something else while the CNC-driven equipment handles the job.

Not only does modern CNC machining create consistent and accurate parts through predictable, repeatable production runs, it also reduces human error and takes the guesswork out of timeline planning and scheduling. With predictability comes the ability to pinpoint on a calendar exactly how long it will take to complete, say, a 1,000-piece run.

Modern CNC machining also allows operators to utilize more efficient techniques. For example, helical milling moves three axes at once — the X axis, Y axis and Z axis — to create a bore on a part. This would simply not be possible with a conventional machine.

New Hiring Opportunities and Simplified Training

Modern CNC techniques also open new doors for labor and personnel management.

Since traditional milling methods require a far more sophisticated and specialized level of skill, it is much easier to hire in the era of modern CNC.

CNC training can be done in house, with an experienced employee showing a new hire how to use the equipment. Recruits used to serve long apprenticeships under master tradespeople with years of experience, but today's new hires need only to learn a few core concepts, such as setting coordinates, setting tools, understanding how to download and run a program, and how to stop if they want to check something.

Engineers and programmers are trained on CAD (computer-aided drafting) and CAM (computer-aided machining) software. They learn how to use CAD to model and draw parts, and they learn how to use CAM to determine the machining parameters, including which tools to use and which metal-removal methods to apply.

Just a Handful of Parts? Probably Not Worth a CNC Setup

CNC technology has revolutionized the milling process, but it usually isn't worth the engineering time required for setup on a run of just a few parts. Generally, when milling a low-production run of fewer than four parts in a standard shape, manufacturers don't reap CNC's repeatability benefits. In those cases, it's usually less expensive and faster to just do it on a conventional machine. It is important to note that this rule only pertains to standard shapes. If even a single part is complicated, it makes sense to use CNC.

CNC machining provides a level of motion control, predictability and repeatability that would have been unimaginable a generation ago. The manufacturers who utilize it create better parts faster and cheaper, and they can further reduce costs and streamline operations through hiring that is much more open and training that is simpler and faster.

Some complex jobs require 5-axis machining, a specialty technique that offers unrivaled precision and flexibility. But 5-axis machining does come with some special considerations. Builders should only work with manufacturers that have the skills and experience to know if this amazing, but complicated, procedure is truly necessary.

What is 5-Axis Machining?

5-axis machining enables machine tools to move on 5 different axes at once. Traditional 3-axis tools are limited to movement on just 2 axes, X and Y, with the tool itself moving along the Z axis.

The 5-axis model adds two additional rotary axes, the A and B axes. This allows operators to move the machine or cutting pieces in different directions without having to move to a new set up. Imagine a square box as a part. A 5-axis tool can access all sides of the box for machining or drilling, while a 3-axis setup only allows access to one side.

There are two kinds of 5-axis machining techniques: 5-sided machining and simultaneous 5 axis.

5-sided machining allows the tool to orient only to the sides of the box. This limits work to 90-degree rotations and requires the operator to position the tool, do the work, then reposition. Simultaneous 5 axis, on the other hand, enables tools to work on all sides at the same time.

Generally, fewer than 20 percent of jobs call for 5-axis machining because of the unique considerations that go along with using this technique.

The Considerations of 5-Axis Machining

While 5-axis machining does offer a number of unique benefits, the complexity of the technique demands careful consideration before implementation:

• It is more expensive.
• It requires specialized training for operators, programmers and planners.
• It requires specialty software.
• There are more variables to consider, such as verifying that nothing is hit with the head and that the operator stays within the travel limits of the machine.

The Benefits of 5-Axis Machining

Once a machinist has determined that the best course of action is to proceed with 5-axis machining, they can expect to see the following benefits on your project:

• Reduction in set-up time. Since the machinist can access all sides of the box, they don't have to spend labor time repositioning the component.
• Greatly improved part quality. Because there is no need for the machinist to clamp and unclamp the part, and instead simply positions the machine, there are no errors created through multiple set ups.
• Parts can be machined more quickly and more efficiently.
• Tools from 3-axis machines can be used interchangeably on 5-axis machines.

When Does it Makes Sense to Utilize 5-Axis Machining?

Some parts call for specialized geometry that can only be created with 5-axis machining, such as impeller blades and fan blades. In other cases, different areas that require machining have an especially tight tolerance relationship with each other. 5-axis machining may also be necessary if a part can't be held in a way that is accessible to the tools.

None of these circumstances are obvious, and only the most experienced manufacturers can identify when 5-axis machining is truly necessary. They have to analyze each job on a case-by-case basis, determine if the technique is appropriate and propose alternative methods when it is not. Since most manufacturers don't own the expensive equipment required for 5-axis machining, builders should make sure their manufacturer has the contacts and relationships required to contract the work out to a reliable vendor.

For jobs that require 5-axis machining, the technique can give machinists an unrivaled level of precision and flexibility for working with specialty parts that have unique geometry or especially tight tolerances. There are enough considerations, however, that it shouldn't be used if the job can be done another way, which is why it is so important to work with a team that understands the process and can identify the situations that call for its use.

When manufacturers possess the skills and sophisticated inspection tools needed to augment the capabilities of their equipment, they can bid on projects that would otherwise be out of reach and pass on enormous savings to their customers.

Surpassing the Limitations of Machines

Some projects require the machining of parts that are too large for the natural travel of a manufacturer's CNC machines to accommodate. To bridge this gap, many manufacturers machine the portion that is within reach, slide the next portion over, machine that portion, slide the next portion over, and so on.

This common technique enables machines to surpass their limited reach, but it also leaves the door open for minor flaws and inconsistencies that are unacceptable in critical-use applications. With inspection tools such as laser trackers, however, the most skilled manufacturers can move parts within the machine's travel with a level of continuity so flawless that it appears that the part was machined in a single setup.

A Reliable, Cost-Efficient Process

Specialty machines designed for use on even the largest parts do exist. They are so cost prohibitive, however, that the hourly rate would put an intolerable financial burden on the customer. By using inspection tools instead, the most experienced and well-equipped manufacturers can achieve identical — or nearly identical — results at a fraction of the cost with their own in-house machines.

The process is reliable and predictable.

When independent inspection tools are incorporated into a machining operation, it becomes possible to account for even the most minor variations in accuracy and repeatability. This enables teams to adjust CNC programs until they produce a feature that is far more accurate than the machine could have produced on its own, even across multiple setups.

These adjustments can then be referenced in later operations to ensure accuracy throughout the remainder of the pattern and setups.

Accurate Quoting, New Opportunities for Bidding

By bringing the most creative technical planners into the bidding process early, manufacturers can review proposals and develop quotes knowing that they are able to stretch the limitations of their machines if the project calls for it.

Once a team knows how to extend the natural reach of its machines, it can surpass the dimensional boundaries of its traditional capability list. Now it becomes possible to place bids on projects that would have otherwise been beyond their ability to complete. Many less savvy manufacturers walk away from jobs that they deem impossible because they don't have an intimate understanding of their machines, and how to augment their capacity through the use of inspection tools.

Most projects don't require machine augmentation. Generally, fewer than 25 percent of jobs call for expansion through the use of independent inspection tools, and those that do usually require this technique on just a single part or two. These are the parts, however, that prevent manufacturers from placing bids.

By pushing their machines beyond their natural limits, manufacturers can expand their capabilities, extend the range of projects on which they can bid and look past their own limitations. By eliminating the need to invest in rarely used, but wildly expensive equipment, they can do the same work for a fraction of the cost. When manufacturers develop this level of mastery over their equipment, jobs that were once deemed impossible become difficult, but doable.