Posts Tagged: Heat Management


Essential Tips for Machining Aluminum Components

Machining AluminumCommon complaints among people new to machining Aluminum alloys include poor surface finish, gummy deposits on cut faces or tool edges, and a smeared appearance. All materials have different properties that require adjustments and care to achieve the optimal finishes.

Aluminum is a soft and ductile metal that has high thermal conductivity. The former means it cuts easily but creates long chips. The latter means it is susceptible to heat build-up. Following these tips when machining aluminum can help mitigate both these concerns.

Use the Right Cutting Tool

Although aluminum is soft and ductile, it requires a good cutting tool for best results. Don’t use high-speed steel or cobalt tools for this job; use carbide cutting tools instead. Also, it is sometimes better to use a tool with fewer flutes. Since Aluminum produces long chips, a tool with fewer flutes will allow chips to escape more easily. Using the right tool with the correct number of flutes will allow you to employ a broader range of spindle speeds.

Keep it Cool

As mentioned above, aluminum has a high thermal conductivity. It gets hot when cut, and that heat can build up fast. This, in turn, can result in a finish with a smeared appearance, workpiece warpage, and leading edge build up (that gummy problem). Proper coolant flow will move chips away from the cutting zone and keep the cutting surfaces properly lubricated.

Horsepower is Your Friend

While aluminum may be softer than other metals, it is still a metal and machining it requires a great deal of power. If your machine can’t keep up with the power requirements for a cut, it will result in chatter and deflection. It may be necessary to use horsepower “derating” in feed and speed calculations when using smaller, lightweight machines for aluminum milling.

A Note on Chip Management

Aluminum’s high ductility results in long unbroken chips that can quickly build up around a tool. This can cause tool breakage, leading edge buildup (more gummy problems) and heat buildup (that smeared finish). When cutting aluminum, be vigilant about cleaning chips. Whether it is with a fixed air blast system, high coolant flow rates or chip conveyors, chip removal should be integrated into your process.

Aluminum is ductile, lightweight, thermally, and electrically conductive with excellent strength characteristics. With a few adjustments to machining techniques, it can be a great material for many parts and projects.


Avoid the Sizzle: Tips to Mitigate Heat Buildup

Milling CoolantIt is the nature of machining to generate heat. The friction between tool and work piece and the acts of cleaving material with a tool and breaking molecular bonds are, in fact, exothermic processes. However, excessive heat generation can shorten tool life, degrade surface finish, cause workpiece and tool warping, and generate toxic smoke.

Follow these tips to mitigate heat buildup in your tools and workpieces

High Efficiency Milling (HEM)

HEM is different from High Speed Milling (HSM) because it is focused on reducing chip thinning and maximizing tool efficiency. The HSM approach is designed to reduce the depth of cut and maximize spindle speed. HEM, on the other hand, aims to optimize tool wear by adjusting the feed rate to maintain chip thickness throughout the operation.

Most notably, HEM mitigates heat build up by cutting with as much of the cutting edge as possible. This distributes the heat over a larger area of the tool. Utilizing the whole cutting edge also reduces tool wear.

Coolant Management

Your first instinct for mitigating heat buildup in tools and workpieces might be to crank up the coolant flow. As the thinking goes:

More Coolant = Cooler Parts

This might work in most cases, but the practice is wasteful. It also does not take into consideration the effects coolant has on part finish, chip evacuation and potential material damage or warpage. It is important to select the right coolant (air, mist or liquid) and the best delivery system for the process. Then, the most efficient flow rate can be dialed in for the best part quality.

In some cases, using coolants may not be feasible. Customer requirements or certain procedures dictate machining dry. For these occasions, refer to this article to find tips for alleviating heat buildup during dry machining operations.

Climb Milling

Traditionally, milling operations put the feed direction and the tool rotation in opposing directions. This method generates a thin-to-thick chip which has multiple adverse effects. It increases the chances of undesirable surface finishes because of chip re-cutting and tool rubbing. It also pushes heat generation into the tool and workpiece.

On the other hand, climb milling puts the feed and tool rotation in the same direction. This generates a thick-to-thin chip. The heat gets pushed the chips rather than into the tool and workpiece. It also improves surface finish and helps push chips out of the part. This makes coolant flows more efficient for heat removal and chip evacuation.

Implementing these tips can ensure you are producing the highest quality parts while preserving your tools.