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Contouring Considerations

What is Contouring?

Contouring a part means creating a fine finish on an irregular or uneven surface. Dissimilar to finishing a flat or even part, contouring involves the finishing of a rounded, curved, or otherwise uniquely shaped part.

Contouring & 5-Axis Machining

5-axis machines are particularly suitable for contouring applications. Because contouring involves the finishing of an intricate or unique part, the multiple axes of movement in play with 5-axis Machining allow for the tool to access tough-to-reach areas, as well as follow intricate tool paths.

 Recent Contouring Advances

Advanced CAM software can now write the G-Code (the step-by-step program needed to create a finished part) for a machinists application, which has drastically simplified contouring applications. Simply, rather than spend several hours writing the code for an application, the software now handles this step. Despite these advances, most young machinists are still required to write their own G-Codes early on in their careers to gain valuable familiarity with the machines and their abilities. CAM software, for many, is a luxury earned with time.

Benefits of Advanced CAM Software

1. Increased Time Savings
Because contouring requires very specific tooling movements and rapidly changing cutting parameters, ridding machinists of the burden of writing their own complex code can save valuable prep time and reduce machining downtime.

2. Reduced Cycle Times
Generated G-Codes can cut several minutes off of a cycle time by removing redundancies within the application. Rather than contouring an area of the part that does not require it, or has been machined already, the CAM Software locates the very specific areas that require machining time and attention to maximize efficiency.

3. Improved Consistency
CAM Programs that are packaged with CAD Software such as SolidWorks are typically the best in terms of consistency and ability to handle complex designs. While the CAD Software helps a machinist generate the part, the CAM Program tells a machine how to make it.

Contouring Tips

Utilize Proper Cut Depths

Prior to running a contouring operation, an initial roughing cut is taken to remove material in steps on the Z-axis so to leave a limited amount of material for the final contouring pass. In this step, it’s pivotal to leave the right amount of material for contouring — too much material for the contouring pass can result in poor surface finish or a damaged part or tool, while too little material can lead to prolonged cycle time, decreased productivity and a sub par end result.

The contouring application should remove from .010″ to 25% of the tool’s cutter diameter. During contouring, it’s possible for the feeds to decrease while speeds increases, leading to a much smoother finish. It is also important to keep in mind that throughout the finishing cut, the amount of engagement between the tool’s cutting edge and the part will vary regularly – even within a single pass.

Use Best Suited Tooling

Ideal tool selection for contouring operations begins by choosing the proper profile of the tool. A large radius or ball profile is very often used for this operation because it does not leave as much evidence of a tool path. Rather, they effectively smooth the material along the face of the part. Undercutting End Mills, also known as lollipop cutters, have spherical ball profiles that make them excellent choices for contouring applications. Harvey Tool’s 300° Reduced Shank Undercutting End Mill, for example, features a high flute count to benefit part finish for light cut depths, while maintaining the ability to reach tough areas of the front or back side of a part.

Fact-Check G-Code

While advanced CAM Software will create the G-Code for an application, saving a machinist valuable time and money, accuracy of this code is still vitally important to the overall outcome of the final product. Machinists must look for issues such as wrong tool call out, rapids that come too close to the material, or even offsets that need correcting. Failure to look G-Code over prior to beginning machining can result in catastrophic machine failure and hundreds of thousands of dollars worth of damage.

Inserting an M01 – or a notation to the machine in the G-Code to stop and await machinist approval before moving on to the next step – can help a machinist to ensure that everything is approved with a next phase of an operation, or if any redundancy is set to occur, prior to continuation.

Contouring Summarized

Contouring is most often used in 5-axis machines as a finishing operation for uniquely shaped or intricate parts. After an initial roughing pass, the contouring operation – done most often with Undercutting End Mills or Ball End Mills, removes anywhere from .010″ to 25% of the cutter diameter in material from the part to ensure proper part specifications are met and a fine finish is achieved. During contouring, cut only at recommended depths, ensure that G-Code is correct, and use tooling best suited for this operation.

What You Need to Know About Coolant for CNC Machining

Coolant in purpose is widely understood – it’s used to temper high temperatures common during machining, and aid in chip evacuation. However, there are several types and styles, each with its own benefits and drawbacks. Knowing which coolant – or if any – is appropriate for your job can help to boost your shop’s profitability, capability, and overall machining performance.

Coolant or Lubricant Purpose

Coolant and lubricant are terms used interchangeably, though not all coolants are lubricants. Compressed air, for example, has no lubricating purpose but works only as a cooling option. Direct coolants – those which make physical contact with a part – can be compressed air, water, oil, synthetics, or semi-synthetics. When directed to the cutting action of a tool, these can help to fend off high temperatures that could lead to melting, warping, discoloration, or tool failure. Additionally, coolant can help evacuate chips from a part, preventing chip recutting and aiding in part finish.

Coolant can be expensive, however, and wasteful if not necessary. Understanding the amount of coolant needed for your job can help your shop’s efficiency.

Types of Coolant Delivery

Coolant is delivered in several different forms – both in properties and pressure. The most common forms include air, mist, flood coolant, high pressure, and Minimum Quantity Lubricant (MQL). Choosing the wrong pressure can lead to part or tool damage, whereas choosing the wrong amount can lead to exhausted shop resources.

Air: Cools and clears chips, but has no lubricity purpose. Air coolant does not cool as efficiently as water or oil-based coolants. For more sensitive materials, air coolant is often preferred over types that come in direct contact with the part. This is true with many plastics, where thermal shock – or rapid expansion and contraction of a part – can occur if direct coolant is applied.

Mist: This type of low pressure coolant is sufficient for instances where chip evacuation and heat are not major concerns. Because the pressure applied is not great in a mist, the part and tool do not undergo additional stresses.

Flood: This low pressure method creates lubricity and flushes chips from a part to avoid chip recutting, a common and tool damaging occurrence.

High Pressure: Similar to flood coolant, but delivered in greater than 1,000 psi. This is a great option for chip removal and evacuation, as it blasts the chips away from the part. While this method will effectively cool a part immediately, the pressure can be high enough to break miniature diameter tooling. This method is used often in deep pocket or drilling operations, and can be delivered via coolant through tooling, or coolant grooves built into the tool itself. Harvey Tool offers Coolant Through Drills and Coolant Through Threadmills.

Minimum Quantity Lubricant (MQL): Every machine shop focuses on how to gain a competitive advantage – to spend less, make more, and boost shop efficiency. That’s why many shops are opting for MQL, along with its obvious environmental benefits. Using only the necessary amount of coolant will dramatically reduce costs and wasted material. This type of lubricant is applied as an aerosol, or an extremely fine mist, to provide just enough coolant to perform a given operation effectively.

To see all of these coolant styles in action, check out the video below from our partners at CimQuest.

In Conclusion

Coolant is all-too-often overlooked as a major component of a machining operation. The type of coolant or lubricant, and the pressure at which it’s applied, is vital to both machining success and optimum shop efficiency. Coolant can be applied as compressed air, mist, in a flooding property, or as high pressure. Certain machines also are MQL able, meaning they can effectively restrict the amount of coolant being applied to the very amount necessary to avoid being wasteful.

Harvey Tool Voted #1 Top End Mill Brand

Rowley, MA – Harvey Tool is proud to announce that for the second consecutive year, it has been voted #1 Most Popular End Mill Brand by participants of the 2016 CNC Cookbook End Mill Survey, a questionnaire meant to gauge machinists’ most preferred manufacturers.

Of the nearly 1,300 votes cast for more than 90 different end mill brands, Harvey Tool earned the top spot with 90.3 percent of voters listing the Rowley-based company as a top choice end mill manufacturer. Following behind were Niagara (whom Harvey Tool tied with for the top spot last year), OSG, Accupro, Garr, SGS, Kennametal, and Micro100.

While the survey focused on overall brand popularity, it also asked respondents to rank end mill brands based on the categories of “combined value and performance” and “highest performance.” Harvey Tool was named the top choice for both categories, tallying 7.9 percent of votes for highest performance and 6.8 percent for combined value and performance. Simply, participants voted Harvey Tool the first choice for tools if money was no factor, while also listing them as having the best balance of performance and value.

Helical Solutions, whom Harvey Tool acquired in 2015, also performed well in the CNC Cookbook End Mill Survey, ranking in the top position within the Tier 2 list of end mill brands. This marks the first year that Helical has been named and ranked in this annual survey.

“We’re extremely proud of this accomplishment as it works to affirm the hard work and commitment our team exhibits every day for our customers,” said Harvey Tool Vice President of Marketing Garth Ely. “The results of this survey clearly express that Harvey Tool is a top choice for machinists, and there’s no better feeling than that.”

“Each member of our team played a vital role in making this possible,” Ely said. “It’s truly a cross functional effort here, which makes an accomplishment of this magnitude so much greater.”

“For us, this is just another accomplishment in what has been a tremendous year of growth and achievement,” said Harvey Tool Senior Vice President of Sales Jerry Gleisner. “To see both Harvey Tool and Helical Solutions perform so well is only added motivation for us to continue to push for an even better product for our customers in 2017.”