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Hand Tools


CAM software, five-axis machining help supplier Delta Tooling come to grips with a high-profile prosthetic hand project.

 

The VISI suite of CAD/CAM applications from Vero Software has been instrumental in helping a precision engineering company develop the world’s most advanced commercially available myoelectric prosthetic hand (i.e., one controlled by signals from voluntarily contracted muscles within a person’s residual limb) currently on the market.

Precision engineering company Delta Tooling Ltd. (West Sussex, UK) was approached some two years ago by prosthetics specialists RSLSteeper (Leeds, UK) to assist in the manufacture of the bebionic3 prosthetic hand, which is transforming the lives of amputees worldwide, helping them to regain independence and control in their everyday lives.

The bebionic3 hand allows its users to carry out a wide range of everyday tasks and is strong enough to carry up to 45 kg.

 

Luke Sywalker-Worthy

RSLSteeper references the Terminator films in its video demonstrating this high-tech prosthetic hand (view at http://youtu.be/_qUPnnROxvY); tech media Web sites are more often and gleefully comparing it to the robotic hand sported by Luke Skywalker at the end of The Empire Strikes Back chapter of the Star Wars saga. The bebionic3 utilizes leading-edge technology to trigger one of its programmed grips, accurately mirroring human movements. The culmination of many years of work from RSLSteeper, the bebionic3 hand is designed so that its unrivalled versatility, functionality and performance allows its users to carry out everyday tasks such as using a computer keyboard, tying shoelaces and chopping vegetables. RSLSleeper press materials for the device promote such features as:

VISI software helped Delta Tooling prepare the geometry for manufacture and create highly efficient toolpaths for the bebionic3 aluminum knuckle.

Individual motors in each finger allow you to move the hand and grip in a natural, coordinated way. The motors are positioned to optimize weight distribution, making the hand feel lighter and more comfortable.

  • Powerful microprocessors continuously monitor the position of each finger, giving you precise, reliable control over hand movements.
  • Fourteen selectable grip patterns and hand positions enable you to perform a huge number of everyday activities with ease.
  • Proportional speed control gives you precision control over delicate tasks, so you can pick up an egg or hold a polystyrene cup as easily as crushing an empty can.
  • Proprietary “bebalance” software and wireless technology located within the hand makes it easy to customize the functions to suit your preferences and lifestyle.
  • Auto grip means no more accidents, as bebionic3 automatically senses when a gripped item is slipping and adjusts the grip to secure it.
  • Durable construction and advanced materials make bebionic3 strong enough to handle up to 45 kg—so you can confidently use the hand to carry heavy objects, and push yourself up from a seated position.

 

Hand-Off to Delta Tooling

Operating from Billingshurst in West Sussex, Delta Tooling now manufactures five parts for the hand, including the aluminium knuckle, the plastic subsection it connects to and a complex thumb bracket that allows the opposable thumb to rotate and move backward and forward.

RSLSteeper originally approached Delta Tooling’s directors Gary Childs and Luke Tetlow with an all-plastic molded product that had to be partly machined when removed from the mold tool. “The initial concept of casting or molding the components, followed by finish machining operations before assembly and testing, gradually evolved into fully machined parts to improve quality and maintain consistency,” says Gary Childs. “Maximizing our use of VISI Machining, we developed strategies that not only machined the parts from solid billets, but produced them in highly competitive times.”

The initial 3 + 2 machining was carried out on Delta Tooling’s range of DMGs and Bridgeports, which were programmed with VISI. However, as the complexity of the components grew, it became clear Delta required the flexibility of full continuous five-axis machining. “We invested in an AgieCharmilles Mikron UCP 800 Duro and updated our machining software to the latest five-axis release of VISI 20,” says Childs. “This not only gives a better quality finish on the product but means we can manufacture it in a more efficient timescale, thereby reducing the number of setups and producing cost-effective production runs.”

Five-axis machining is highly suitable for manufacturing the bebionic3 products, and VISI provides Delta Tooling’s operators with a productive solution for preparing the geometry for manufacture and creating the highly efficient toolpaths required to manage the increasing complexity of the components involved, according to Childs.

CAD data is readily imported into VISI in whatever format the customer supplies it, whether it’s a STEP, IGES or Parasolid file. “We carry out various checks on the file to ensure its integrity, before laying it out in a way that can produce the component from the machine tool’s point of view. Then we’ll assess the part’s machinability,” Childs explains. As part of that process Delta Tooling finds VISI Machining’s collision control and kinematic simulation extremely valuable. “Having made a major investment in a new five-axis machine, the last thing we want is to cause a collision. We always run full-kinematic simulation prior to any production run.”

 

Automatic Toolpath Trimming

A new feature in VISI 20, which Childs says represents “a huge step forward” for them, is the dynamic incremental stock (DIS) command that automatically creates the stock model from the uncut material of previous toolpaths, to be used as reference data for subsequent milling operations. It automatically trims the toolpath to remove unnecessary movements and fresh air cuts. “This allows us to machine rough from one side of the component. When we turn it over we have a new machining cycle that allows us to rough again, but we’re not cutting fresh air” Childs notes. “This reduces machine cycle time further, making us even more efficient.”
Machining the aluminum knuckle for the bebionic3 at Delta Tooling.
Having their roots in mold and press toolmaking, Delta diversified into producing fully machined parts, honing their skills with critical components for a number of F1 sector customers and waveguide components for space satellites. “The combination of our five-axis machines and fully integrated VISI CAD/CAM package means we can react extremely quickly to our customers’ demands—especially the motorsport industry,” says Childs. “For this reason, it is imperative that the [members of the] VISI support team are able to react equally as quickly and they have never let us down. It’s clear they understand our industry and our manufacturing needs.”

The Mikron runs almost constantly across two shifts from 8 am to 2 am the following morning, manufacturing to a call-off order for RSLSteeper on a monthly basis, as well as machining components in additional production runs for Delta Tooling’s motorsport customers.

“We’ve built a solid reputation based on our speciality of producing complex parts with a very quick turnaround time, and a number of customers have been with us for several years. VISI has already helped us make our mark as a company in the three-axis marketplace and now the combination of the new five-axis Mikron machine tool and VISI five-axis machining is making us even more efficient and very competitive.”

The bebionic3 was unveiled in the US in September 2012, and subsequently introduced to the UK at a London launch in November. It looks as if RSLSteeper’s design innovation along with VISI and Delta Tooling’s expertise will ensure the product’s future progression and manufacturing for a long time to come, maintaining RSLSteeper’s vision of improving amputees’ lives.


Edited by Yearbook Editor Michael C. Anderson from information supplied by Vero Software Group.


Published Date : 12/11/2013

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