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A cut above – taking the grind out of the workload

An improved level of control in their world-renowned grinding manipulators, has resulted in the ability to adopt diamond disc technology to improve disc usage and provide an even greater level of efficiency and cost saving on machining and finishing applications says Clansman Dynamics. The proven technology has now been verified by the world-leading KIMURA foundry group in Japan, which reports significant “typical” time savings and improved production efficiencies since installing the Clansman C620G 75kW grinding manipulator, which incorporates diamond-tipped discs rather than resin-based discs.

Problems associated with resin-based discs centre around the erosion of the disc itself when cutting and grinding the casting. Derek Muir of Clansman explains: “The resin disc material wears away during continued use to the point where a 600mm disc can wear down to a 250mm disc. To work at its optimum efficiency, the speed must be continually adjusted to the new size of the disc, so that the tangential speed remains constant. Typically, this would require the spindle rpm to increase from 2,550rpm to 6,000rpm. This is very hard to achieve in practice. However, diamond-tipped wheels don’t wear as rapidly (loss of diamond coating), so they last longer, the second advantage is that the speed doesn’t need to be constantly adjusted because the diameter of the disc isn’t changing and the efficiency is kept to the optimum.”

Until recently Clansman hadn’t been able to take advantage of diamond tipped disc technology because they didn’t feel confident their grinder could achieve the optimum fine control performance required as the company’s machines aren’t fully automated. However, thanks to improvements in integrated connectivity control through a PLC-based control system, the now semi-automated machines are suitable for the upgrade to diamond discs and the host of benefits the technology enables. Part of the initial dilemma is cost. Andrew Allan of Clansman explains: “Of course diamond-tipped discs are more expensive. They cost roughly four times as much as resin-based discs, but they are more efficient and last around ten times longer.”

Improved cutting ability and surface finish

Automatic and semi-automatic grinding manipulators are preferred over hand grinder technology because diamond discs cut to a greater degree. Conventional high frequency hand cutters have only 50mm cutting length per cut, resulting in multiple cuts for most risers. With the Clansman grinding manipulator (incorporating diamond discs), the usable depth on a 300mm disc is 80mm and on a 500mm disc is up to 180mm. Allan says the reliability for cutting is also crucial: “The available cutting depth is constant throughout the disc’s lifetime. ”In addition, use of the grinding manipulator results in a better surface finish. Often just one single cut is required.

Efficiency and productivity

KIMURA Foundry reports that using a traditional combination of hand cutter and grinder, castings take on average 40 hours to finish but with the introduction of the semi-automatic Clansman grinding manipulators this has improved to less than 30 hours. Muir is confident this can reduce even further with experience. “The actual cutting/grinding time when compared with doing the process manually is much faster. Currently, more time is spent handling the casting as the customer finds the best way to present the casting to the manipulator. KIMURA has only been operating the grinder for about six months, so there is a learning curve. The efficiency is improving week by week.”

Some of the tools developed for the Clansman grinder have facilitated additional material and time savings, such as the plane of control and grinding/cutting depth control. Muir explains: “These tools work well with the diamond wheel because they allow the operator to set the cutting plane close to the parent material and the operator doesn’t have to re-set because the disc isn’t wearing away. This enables a higher percentage of the metal to be removed, with the confidence that the casting parent material will not be damaged. This reduces the customer’s requirement for final machining – it’s a win/win and helps with the whole throughput of the castings.” Muir explains that the technology is predominantly for cast iron because the process releases carbon and thus acts as a lubricant, so the heat in the area is manageable.

Of particular note is that KIMURA underwent the investment during the recent Covid-induced travel restrictions. However, Clansman technology and support is not new to Japan. “The first machine we ever sold went to Japan, 25 years ago,” says Allan. “KIMURA are a hugely respected foundry group from both a domestic and worldwide perspective and we are delighted to have been working with them on their investment. Already we are installing another manipulator for a second Japanese foundry in the Autumn, and we hope to continue our expansion in the Japanese market.”

In a statement, KIMURA foundry explained the confidence in the technology, despite the remote installation and commissioning. “…we were originally quite afraid of the work without Clansman TA present on site. However, with all the latest IT communication tools such as Microsoft Teams, we could manage to finish the installation process without major problems, even for the complicated grinding manipulator. Further, once the manipulator power was turned on, we could use eWon (a device for remote access of PLCs) connection and it was superb Clansman could remotely set up the manipulator setting and diagnose the status. It also made commissioning work no problem while your controls engineer could do all the work remotely. I think the eWon connection is essential for the Clansman manipulator and a huge benefit to the customers.” 

All-round success

KIMURA reports that several improvements in production and the finishing process have been gained since installing the Clansman C620G 75kW grinding manipulator:

  • Cutting plane makes it easy and quick for cutting of gates, risers, runners.
  • After cutting, the grinding plane can finish, clean and flat surface.
  • Improved efficiency and productivity helps to reduce operative’s working hours.
  • Safety is much improved compared with hand cutting and grinding.
  • The operative’s working environment is improved significantly.

The C620G is the largest grinder in the Clansman range. The machine excels at large castings and heavy grinding and has a wide-ranging axes of movement – vertical, horizontal, slew, yaw, pitch and roll. The grinding head on the C620G machine is large to allow it to transmit its full power potential efficiently. Add to this the option for diamond tipped disc technology and the efficiency and capabilities increase further. The C620G is designed for 55 to 110kW grinding power, it is part of a range which includes the G30P grinder with 30kW grinding power and the G45 grinder with 45kW grinding power.

Contact: Derek Muir, sales director, Clansman Dynamics, Tel: +44 (0) 1355 579 900. Email: [email protected] web: www.clansmandynamics.com