The challenges that the aerospace sector, in particular, presents motivates manufacturers to generate more inspired solutions to meet customer demands. Contributed by Sutton Tools
Melbourne-based Sutton Tools has never been hesitant about the expansion of its global markets. To its credit, the manufacturer has recently delivered increased productivity gains for a European aerospace customer.
Jeff Boyd, export manager of Sutton Tools said, “Our business has been built on tackling the most challenging demands for tools, and the aerospace sector is a prime example of an industry that constantly demands sophisticated solutions. However, it’s a tough market where there is a lot of competition and success is based on the ability to prove productivity gains.”
Several aerospace component producers in France had been buying a competitor’s brand, leading the Sutton Tools European office to identify an opportunity to manufacture a better performing solution and in doing so, win the business by delivering a 20 percent productivity gain for the customer. Continual demand to lower costs through productivity is a key issue for the aviation and aerospace industries, with customers emphasising the need for reliance on tool stability so they can confidently forecast their production schedules and reduce machine down time.
“We recognised that development of specific aviation industry cutting tools is critical. These tools need a longer life and faster cycle times when working with high strength materials such as titanium and Inconel,” Mr Boyd said.
“The customer’s needs focused on solid carbide milling cutters between 12 to 20 mm that could deliver stable performance across a range of applications,” recounted Mr Boyd. The search commenced for a solution with full understanding that the demands of the industry meant that the company had to push the boundaries of its design and manufacturing technologies across its entire knowledge base of microgeometry, materials, coatings and micro-finishing of surfaces.
Pushing the Envelope To Produce Smarter Tools
The engineering team at Sutton Tools focused on the need for a smoother, high precision surface finish which would also strengthen the adhesion of the tool coating. To achieve the high finish needed, test results were compared from grinding tools using the tool maker’s traditional Anca ball-screw movement machines with an Anca linear motion tool grinder.
The team also experimented with different grinding wheel grades and grinding parameters to determine the best possible finish. After studying surface roughness of the tools, it was discovered that the output from a linear motion grinder could achieve a higher accuracy of surface finish than ball-screw machines.
To validate grinding methods, an optical 3D scanning technique was utilised to measure the surface area roughness at 100-1 magnification on the rake face and cutting edge on the tools. This 3D technique enabled the quality levels to be managed to a considerably high level of accuracy.
“The intensive engineering approach by our team produced a successful outcome for the customer by improving their productivity,” Mr Boyd stated, adding also that such a process has effectively demonstrated that Sutton possesses the capability of being a reliable aerospace industry supplier.
While Sutton Tools operates advanced manufacturing facilities in the Netherlands and India, it is the Melbourne factory that has carried out the whole evaluation process and produced these application-specific end mills for the French aerospace market.
In the past, titanium was not easy to machine. However, since this material has been adopted in many industries, the experience amassed by fabricators gives us lots of titanium machining insight. Today, titanium can be fabricated just as simply as stainless steel.
Here are some noteworthy things when machining titanium:
- Recommended cutting speed. This should be less than 60 m/min for roughing and three to four times that when finishing. Otherwise, thermal softening as well as chemical reaction between tool and workpiece, may occur. Feed rates are entirely dependent upon chip loads as well as other elements, but should be large enough to prevent work hardening. Follow cutting tool manufacturers’ recommendations.
- Titanium conducts heat very slowly. During machining operations, poor thermal conductivity traps heat in the work zone, severely compromising cutting tools. If your machine setup can handle the additional load, consider raising the feed rate to transfer more heat into the chips.
- High heat and stringy chips. Because of this, a copious flow of clean cutting fluid is required.
- Titanium is extremely tough. Use positive rake geometry. The cutting tool must be sharp and should have a tough substrate and hard coating.
- Filtration to 25-micron or better is critical. Increasing its concentration to at least 10 percent, and installing a high-pressure pump of 500 psi or more removes chips from the work area. Using coolant-fed cutting tools with inserts enhances chip control. Investing in a high-quality machine tool is key if you are serious about titanium.
- Titanium will grab end mills under heavy loads. This leads to scrapped workpieces and broken tools. Getting no-fail toolholders for your cutters, and hydraulic vises with hardened and ground jaws for clamping titanium parts, remedies the issue.
- Develop a sound machining procedure prior to the first cut. All of the part features should be analysed, taking special consideration of unsupported areas, tall or thin walls and difficult to reach features. Planning your moves carefully by utilising the right cutters, feeds and speeds, and generating toolpaths helps meet the above conditions.