2 Key Components Truly Optimize Machine Utilization

By Manfred Lenz, Manager – Drilling Products, NAFTA

Maximum productivity and profitability in machining operations hinge on two key components of machine tool utilization. The first is to maximize the amount of time the machine is available to actually cut metal. The second, which is often neglected, is to then make the most productive use of that time. 

Maximize available time

Machines are on the shop floor 8,760 hours (365 days) a year, but their productive availability is much less than that. For instance, a year of five-day, single-shift workweeks, and taking into account time lost to holidays and other interruptions, equates to approximately 1,300 or 1,400 hours of actual available machine time. However, programming and setup further consume a portion of that time.

To shorten a machine’s non-cut time as much as possible:

• Use strategies such as offline programming and modular setups 

• Streamline tool handling with tool magazines and automatic tool changers

• Quickly load and unload workpieces with robotic work handling and/or pallet changers 

Make efficient use of time 

Once available to cut time is maximized, manufacturers must use that time efficiently, which means to produce as many parts as possible and at the lowest cost. To accomplish this, machines, while in the cut, should run at their full potential/capabilities but without exceeding safe limitations. 

Average Time Spendings on a Machine Tool 

Keep in mind that some elements of the machining process are unchangeable. A component’s final application determines the raw material from which it’s made, and the material’s machinability, in turn, dictates basic cutting parameters. For example, the poor thermal conductivity of titanium alloys requires that machines run at lower cutting speeds and feedrates to minimize heat buildup. 

Machine tool capabilities are also a given, because changing the machine is rarely an immediate option. Manufacturers recognize these factors when estimating production costs. However, significant differences between estimated and actual costs can result from inaccurate evaluation of machine tool characteristics and the application of cutting parameters that are impossible to sustain. 

There are some common strategies applicable to all machining operations for establishing initial cutting parameters that will contribute to efficient machine use.

• Select cutting tools with substrate material, coatings and edge geometries that are best suited for the workpiece materials and intended machining operations.

• Apply the tool’s recommended minimum cutting speeds to prevent tool breakage, ensure proper chip formation and limit heat generation.

• Increase feedrates and depths of cut as high as possible without compromising workpiece surface finish.

• Recognize the power and stability characteristics of the machine tool.

By concentrating on maximizing machine tool availability and making the most of that time, you can increase both productivity and profitability in your machining operations. For more ideas on how to effectively manage your tools, please feel free to contact me.  

About the Author

Manfred has been with Seco for more than 16 years. In his current role as drilling product manager, he is responsible for every aspect of the company’s drilling products in North America. He works closely with global R&D on new innovations to ensure they meet the market’s tough manufacturing demands. Manfred also supports the Seco sales force by providing them with technical information and cost saving solutions that bring value to customers. In his spare time, he enjoys boating, bowling and golfing.

Best Practices for Effective Chipbreaking

By Chad Miller, Product Manager – Turning and Advanced Materials

MR6 chipbreaker for medium-rough turning

Chips can be extremely detrimental to your tools and production process, especially long chips formed during turning operations. The good news is there are tooling solutions and best practices for dealing with problematic chips.

By way of background, it’s important to understand what causes chips and the problems they create. Long, stringy chips commonly form when machining materials with low amounts of carbon, such as mild-steel and austenitic stainless steel. These types of materials are soft and gummy, and do not form martensite that would allow their chips to easily break away.  

When these types of chips form, they can tangle around the tool and workpiece and form bird nests, which can increase heat in the material that, in turn, leads to poor surface finishes, tool breakage, machine downtime and thus increased production costs. A build-up of chips hinders process efficiency and creates safety issues. Operators must stop machines to untangle dangerously sharp chips from around tooling as well as constantly empty chip hoppers. Not only are these extra steps time-consuming, they make unattended lights-out operations impossible.  

Today’s chipbreaking technology eliminates many of these issues by effectively controlling the formation of chips so they break off and move out of the cut zone. Here are a few general chipbreaking best practices:

MF2 chipbreaker for semi-finishing and finishing

• Match the chipbreaker to the application. The first basic rule of controlling chips is to understand that not all chipbreakers are alike. There are many different shapes and geometries of inserts available in positive and negative rakes. Proper selection depends on the type of workpiece material and turning operation being performed. 

When finishing, for example, strict chip control is essential. Finishing chipbreakers are specially designed for smaller depths of cut usually less than 0.060" and relatively low feed rates of 0.003"-0.012" in/rev. These chipbreakers are narrow in the front and have a pit or dimple and a very large rake angle at the nose. Compare this to a roughing chipbreaker, which typically has negative T-lands for edge strength and for breaking chips at heavier depths of cut. 

However, whether roughing or finishing, the key to truly effective chipbreaking is the right combination of tool geometry, grade and coating paired with proper coolant, all of which is based on the application at hand. 

• Increase the depth of cut, if possible. Depth of cut significantly affects chip formation. Smaller depths tend to produce spiral-shaped chips, while larger depths generate the more desired comma-shaped chips. To create chips that break off and quickly evacuate, cutting tools should run at their maximum allowable depths of cut. 

• Increase the feedrate. One of the most common mistakes machinists make is not feeding tools hard enough, which often results in poor chipbreaking. As a rule of thumb, the minimum feed rate in turning applications should not be less than the chipbreakers recommend feed rate, and the maximum feed rate should not exceed the tool’s nose radius to ensure ideally shaped chips.

These are just a few of the general considerations for effective chipbreaking. At Seco, we have a complete assortment of chipbreaker geometries that includes both negative and positive rake inserts and can help you find the right solution for each of your applications. To learn more or discuss a specific chipbreaking challenge, please feel free to contact me.

About the Author

Chad manages Seco's turning and advanced materials product lines, including all CBN and PCD products. When he's not helping customers implement advanced metalcutting solutions, you can find him training for and running 5K, 10K and 1/2 marathon races and triathlons.