A-Tap simplifies tool management and accelerates productivity in pump component production
Founded in 1933, Gorman-Rupp Company is a world leading manufacturer of pumps and pumping systems. Gorman-Rupp produces pumps for a wide variety of markets, such as municipal, sewage, industrial, mining, construction, petroleum, agriculture and more. The company’s extensive line of pump products includes self-priming centrifugal pumps, standard centrifugal pumps, submersible pumps, trash pumps, priming assisted pumps, rotary gear pumps and air-driven diaphragm pumps.
Founded in 1933, Gorman-Rupp Company is a world leading manufacturer of pumps and pumping systems. Photo courtesy of Gorman-Rupp.
Employing 100 staff, Gorman-Rupp’s headquarters is located in Mansfield, Ohio, United States, with over one million square feet of modern manufacturing and warehousing facilities. Gorman-Rupp’s pumps are generally made of cast iron, bronze, AISI316 cast stainless steel (JIS SCS14A) and ASTM CD4MCu (duplex stainless steel) to handle corrosive and abrasive fluids. With a fleet of state-of-the-art, fully automated machining centers, high-speed, high-quality machining of pump castings are made possible.
Since nearly every part produced includes drilled and tapped holes, it is no surprise that over the years, Gorman-Rupp has utilized nearly every type and brand of tap available. While Gorman-Rupp produces a wide variety of pumps, a great deal of commonality exists on the component level, allowing the production of “part families” with minor differences such as part size, hole location, material, etc. The number of holes required to be processed vary per part due to the high-mix, low-volume nature of the production. This has resulted in having many duplicate tap configurations as well as a large mix of taps in Gorman-Rupp’s tool crib. The company’s collection of taps ranges from general-purpose to high-performance that are made by various cutting tool manufacturers.
Gorman-Rupp’s extensive line of pump products includes self-priming centrifugal pumps, standard centrifugal pumps, submersible pumps, trash pumps, priming assisted pumps, rotary gear pumps and air-driven diaphragm pumps. Photo courtesy of Gorman-Rupp.
The large variety of taps presented a challenge to Gorman-Rupp, as it does in many other machine shops. Machine operators often would choose the first tap they find from the tool crib that matches the thread designation, which may not always be ideal for the material or the application, resulting in mediocre results.
To address this problem, Gorman-Rupp contacted OSG in hopes of consolidating its tap selection to a more versatile product that works in all the materials that the company uses in its production of pump housing and various pump components. CNC Programmer Tym Greenwood led the project on the Gorman-Rupp side and laid out the goals of not only consolidating tooling to one manufacturer, but also increasing tapping efficiency and reducing overall cost per unit (CPU). It was important to Gorman-Rupp to streamline its tap selection in a way without sacrificing part quality or CPU.
After reviewing the list of taps Gorman-Rupp had used in the past 12 months, becoming familiar with the parts and manufacturing processes noting the common materials, OSG saw an opportunity to utilize the A Brand A-Tap series.
OSG’s A-Tap is an all-purpose tap series designed to simplify tool management and to excel in a wide variety of materials and applications. Achieving trouble-free chip evacuation with a spiral tap in blind holes is particularly challenging and is a main cause of headaches for many manufacturers. To resolve this problem and to improve the ejection of chips, OSG’s A-Tap A-SFT has adopted a variable helix flute design, which encourages stable chip evacuation. The helix angle changes from the chamfer, where chips are formed, to the flutes, where chips are evacuated. This unique geometry enables greater chip control that can help produce tightly compacted chips for easy ejection from the hole.
The A-Tap is known for its superior chip evacuation capability. It is an all-purpose tap series developed to accommodate a wide variety of materials and machining environments, helping manufacturers simplify tool management.
To accommodate a wide range of cutting conditions, powdered metal HSS and OSG’s V coating have been employed in this series to achieve excellent wear resistance. In addition, to enable high-speed machining, the A-Tap series incorporates a unique cutting edge design that emphasizes sharpness. Not only does the A-Tap series perform well in general steel, it also excels in difficult-to-machine materials such as stainless steel and mild steel. The A-Tap is compatible with various types of machining equipment – from manual machines to the latest advanced machining centers. Available in spiral flute and spiral point, the A-Tap can efficiently tap nearly any material, making it the most versatile, high-performance tap on the market.
The unique features of the A-Tap make it a perfect choice for Gorman-Rupp to utilize in its tap consolidation project. Once the A-Tap was identified as a potential solution, the highest usage taps were brought in for testing on a variety of machines, materials and applications.
For a AISI316 cast stainless steel (JIS SCS14A) application, testing took place on a Mazak 630 horizontal machining center using OSG’s 3/8-16 UNC modified bottoming A-SFT spiral flute tap (EDP# 1650511608). The drill hole size was 0.323-in (blind hole) and the tapping length was 1-inch. Soluble coolant was applied for the machining. The cast stainless steel housing part has an estimate annual production of 25,000 pieces. Both the competitor spiral flute tap and OSG’s A-SFT were used at a spindle speed of 200 rpm, cutting speed of 19.63 sfm, feed rate of 0.0625 ipr and 12.5 ipm. The cycle time was 9.6-second. The competitor tool life was 250 pieces whereas OSG’s A-SFT was able to complete 300 pieces. The tool price of the A-SFT is also about $8.5 less than the competitor tool. Taken in consideration of the tool cost, machine cost, tool change time and other factors, the total CPU is reduced by 8 percent versus the competitor tool.
OSG’s 1/2-13 UNC modified bottom A-SFT spiral tap demonstrates superior performance in AISI316 cast stainless steel (JIS SCS14A).
For a ductile cast iron application, testing took place on a Mazak 630 horizontal machining center using OSG’s 1/2-13 UNC modified bottoming A-SFT spiral flute tap (EDP# 1650512708). The drill hole size was 0.437-in (blind hole) and the tapping length was 1.25-inch. Soluble coolant was applied for the machining. The cast iron housing part has an estimate annual production of 25,000 pieces. The competitor spiral flute tap was used at a spindle speed of 350 rpm, cutting speed of 45.81 sfm, feed rate of 0.077 ipr and 26.95 ipm. The cycle time was 5.6-second and the tool life was 400 pieces.
OSG’s A-SFT was used at a spindle speed of 530 rpm, cutting speed of 69.38 sfm, feed rate of 0.077 ipr and 40.81 ipm. The cycle time was 3.7-second and the tool life was 600 pieces. The tool price of the A-SFT is also about $12 less than the competitor tool. By switching to the A-SFT, Gorman-Rupp is able to improve 1.5 times the tool life and reduce cycle time by 34 percent. Taken in consideration of the tool cost, machine cost, tool change time and other factors, the total CPU is reduced by 38 percent versus the competitor tool.
Superb thread finish by the A-Tap. Gorman-Rupp is very pleased with the thread quality left by the A-Tap compared to their previous tooling choice. Even in grey cast iron, the thread finish is exceptional.
The above CPU reductions combined with the convenience of having only one tap style that works for all materials showed Gorman-Rupp the value of the A-Tap series.
“The positive results we are getting combined with the local support make the decision to choose OSG as our primary tap provider an easy one,” said Tym Greenwood, Gorman-Rupp CNC Programmer and Project Manager.
Based on a number of tests conducted, Gorman-Rupp concluded that a 20 percent cost reduction versus the prior year can be achieved on all tapping operations. Since then, Gorman-Rupp has converted all of its standard taps to the A-Tap and will continue to further drive efficiency and cost reduction across all areas of the machine shop.