The pump and valve industry in India has been growing steadily, thanks to its broad-based application in almost every segment. Indian manufacturers are leveraging this enormous potential not just for meeting domestic demands, but also spreading their footprint in the global arena through exports. Apart from the simple and standard models, there is an increasing demand for high-quality and future-ready valves with electro-mechanical actuators for automation and monitoring, in accordance with Industry 4.0 standards.
The complexity involved in manufacturing such valves is further heightened by the need for manufacturers to meet the stringent criteria of global certifying agencies like API (American Petroleum Institute).
Let us take the example of a triple offset butterfly valve which involves complex machining owing to its intricate design and geometries. Triple offset butterfly valves (TOV) have three separate offsets as shown in Fig. 1. Two offsets are at the center while the third is on the seating surface which creates a cone type shape out of the disc and the seat. These valves are used mostly in applications where a tight shut-off is required, a high temperature is expected, or hard sealing surfaces are required with zero leakage (soft seat) or rated leakage (metal seat). As you can see in the image below, the angle of the seat keeps changing constantly along the circumference, the section A has a 20°+20°angle symmetrically, but it changes to 35°+ 5°, at sections B-B. Also, the relative accuracy of the stem bore, and the valve seat plays a critical role in the performance of the valve.
The success of machining such a valve that delivers the desired performance is hugely dependent on the machining process. To enable customers to address the said complexities associated with valve manufacturing, WIDMA, the Machining Solutions Group of Kennametal India Limited has developed multi-tasking machines to perform operations such as turning, milling, drilling, boring, and tapping, all in a single setup.
The machine is powered by a 30/37 kW work spindle operating with a speed ranging from 5 – 350 RPM, which enables a very high material removal rate, while the tool spindle is powered by a 25kW motor. The spindle head can swivel from +90° to -90°. This rotation of the spindle facilitates the movement of the tool and generates complex angles and shapes on the component. The rigid base and column make the machine ideal for a valve manufacturer, given the huge size and weight of components to be mounted.
Let us now compare WIDMA’s VU1150 with a conventional machining setup. A traditional manufacturing facility for the butterfly valve, requires one Horizontal machining Center, a Vertical Turning Lathe, and 1 Vertical Machining Center to perform a similar operation. A total of five setups are required to cover the entire process for a double offset valve and 6 setups for a triple offset. One of our customers informs us that they take up to four hours to change a setup. Now, if there are 6 setups to be done, it takes 24 hours only for a setup change since there are
three machines, the work-in-progress inventory is usually high enough to feed all three machines.
The triple offset seat that is to be machined is usually made such that the fixture has a predefined angle upon which the component is placed at an inclined position and then turned to achieve the required slope. This creates an intermittent cut for the component, reducing the life of the insert. All these issues are addressed in the VU1150 machine.
The VU1150 requires just two setups to complete the entire machining operations, right from the cast to the finished component, reducing the overall setup time of the process. Also, the relative accuracy is achieved as the component is not disturbed between operations, eliminating the cumulative misalignment that is gathered due to multiple load-reload during setup change. We have achieved relative accuracies superior to the industry requirement of 0.05mm or 50µm.
To cite a success story, DelVal Flow Controls Private Limited, a leading manufacturer of valves replaced their existing setup with WIDMA’s VU1150 and achieved the following results:
Conventional Process | Process with WIDMA VU1150 |
5 setups for double offset models 6 setups for triple offset models | 2 setups for most models in WIDMA VU1150 |
Time per set up – 4 hours. For triple offset model – 6 x 4 hours = 24 hours | Time per setup – 5 hours For triple offset model – 2 x 5 hours = 10 hours approximately |
Number of machines required to finish the process – 3 (1 VTL 600 table, 1 HMC and 1 VMC) for 12” model | Number of machines required for complete process – 1 |
| Accuracy decreases due to the compounding effect over five setups, impacting the final product quality. | Accuracy is far superior due to a single setup change, yielding desired product quality |
| Higher asset, manpower, and other WIP material costs | Lower asset, manpower, and other WIP material costs |
| There is lesser control on the lead time, hence delivery time to the end customer due to multiple dependencies and processes involved | Better control on the lead time hence delivery time to end customer due to single machine dependability |
| Cycle time (triple offset machining) – 3.2 hours/component | Cycle time (triple offset machining) – 1.5 hours/component |
| Difficult to program, separate investment needed to buy software to generate CNC codes | Integrated and customized CAM proprietary software for generating CNC codes based on profile and dimensions |
WIDMA is continuously enhancing its products and services to help customers produce high-quality products with optimum efficiency. WIDMA’s customers find these machines an excellent substitute for imported machines.
WIDMA is a leader in providing customized metal-cutting CNC machines that offer high accuracy and productivity across industries. Founded in 1984, WIDMA diversified into customized, semi-standard, and standard machines for machining requirements, ranging from micro tools to large structural parts for the locomotive and general engineering industries. Working with some of the world’s most notable brands, WIDIA is recognized for high-performing machines that deliver on metal removal rates, drilling speeds, and depths.
For more information, visit https://www.widma.com/.
