No Chip, No Bird Nesting

XPF form tap eliminates operation disruption and safety risk

Valdir Lima  |  OSG Sulamericana

When you think of high hazard industries, where people can easily be injured or killed in their work environment – what comes to mind first? According to the Bureau of Labor Statistics (BLS), construction, mining, transportation and manufacturing rank top in the list. The manufacturing industry in particular, often involves the handling of complex machinery, large and heavy parts, sharp blades, and the moving of components at high speeds, all of which contribute to the high risk of work injuries. According to the BLS, approximately 40 percent of workplace injuries in manufacturing are associated with the contact of objects and is the number one cause of injuries. Overexertion ranks second and constitutes 24 percent of the total work injuries based on a 2011 survey with 114,327 cases of incidents.

At Valtra Inc., in addition to providing value-added services and solutions, the health and safety of its employees and customers are a top priority. Valtra, a worldwide brand of AGCO Corporation, is a leading manufacturer and service provider of agricultural tractors. Valtra tractors are sold in over 75 countries and are known for their reliability, versatility, durability and Nordic roots. Valtra tractors are designed to withstand the harshest climates and deliver high performance even in the toughest working conditions.

Valtra manufacturers 24,000 individually tailored tractors each year and employs approximately 2,100 employees worldwide. Valtra enjoys a growing reputation in South America and is serving the region from its Mogi das Cruzes, São Paulo state-of-the-art facility with approximate 140,832 square meters of production floor and 930 employees.

In the production of fuel tanks in SAE 1020 steel, where holes are required to be threaded, Valtra was encountering tap breakage due to the formation of bird nesting, in which cut chips ejected during operation would wrap around the workpiece, quickly disrupting the tool path. These fuel tanks are made for tractors of small, medium and large sizes. Valtra has been producing these parts for more than 20 years. There are 35 blind holes at a depth of 34 mm per workpiece with a tolerance requirement of 6HX.

Valtra was using a HSSE M16 DIN 376 TiCN coated spiral fluted tap with a 45-degree helix to thread the part with welding points near the threads. When the problem arises, the machine would have to be stopped, which delays production time and is costly to the company. Moreover, the material of the workpiece is malleable and the formation of the spiral chip was causing a safety risk to its employees as the problem requires manual removal of the tool and cut chips. When other tool management providers failed to improve the situation, Valtra’s applications engineer Jeferson Barreto contacted OSG.

Instead of using a spiral fluted tap, OSG proposed the HSS-Co M16 DIN 376 S-XPF forming tap with V coating. Initially, Valtra was hesitant because all the competitors have already tried forming taps with no success. However, the XPF won confidence by demonstrating its ability to perfectly thread external hardened weld points and hardened materials. The XPF is uniquely engineered with a low-torque design to facilitate longer life at faster speeds. Its V coating also enables extreme wear resistance. Engineered to generate up to 50 percent less torque versus other forming taps, the XPF is capable of tapping materials up to 35 HRC and sizes up to M45 in diameter. 

During the trial, both the competitor tap and the XPF were set at a cutting speed of 20m/min, 398 rpm, at a feed of 796 mm/min. Success was measured by tool wear and stability. The XPF completed 10 tanks in the first day of production, without wear marks or high torque problems. The test continued for about a year, with weekly follow-up procedures observing all aspects including torque, quality and tool life that were approved by Valtra’s quality control division. The XPF finished the tests with the M16 and M12 sizes range with tool life surpassing the competitor record of 50 tanks to 350 tanks, which is seven times the tool life. The competitor tool also had to be removed frequently for chip removal; while the XPF maintained excellent thread quality throughout. In addition to the significant gain in tool life, the headache of tool breakage and bird nesting were completely eliminated.

“The technical support offered by OSG helped us discover a new effective solution in our process,” said Valtra Applications Engineer Jeferson Barreto. “In addition to the cost benefit, the safety of our employees is a priority for AGCO, and this partnership had allowed us to improve and guarantee a more profitable and safe process.”