FEATURE ON WORKHOLDING

High-pressure clamping with Piranha vice

Now added to the portfolio of Leader Chuck Systems is the Piranha Clamp range of centring vices. The Swiss-manufactured vices replace the usual dovetail guides found on many vices with parallel, twin cylindrical jaw guides that are said to offer better precision and clamping force.

Designed to act much like a hydraulic press, the hardened and coated spindle guides provide an increased surface area for load distribution, while the drive spindle has been tested to withstand pressures above 1300 Nm². This capability supports high-pressure workpiece clamping with a minimal depth of just 3 mm, so material waste is kept to a minimum.
The nature of the twin-guide design results in an open construction for easy chip evacuation, with any swarf flushed away by the coolant. Another benefit of this concept is an extremely low overall height, so that operators can make the most of the available working envelope.
A built-in zero-point clamping system on the base of the Piranha Clamp provides the interface with the machine tool’s work table and achieves a repeatable loading accuracy of 0.01 mm. However, the quick-change location system can be specified to fit any zero-point design, with adapter plates making the vices totally interchangeable.
Two base sizes are available, the Piranha Clamp 170 is 170 mm long by 90 mm wide, while the larger Piranha Clamp 300 is 300 mm long by 120 mm wide.
Tested against established vices that use pre-stamped raw material, the deflection measured in the Piranha Clamp range is just one-tenth of that measured (at the same clamping pressure) in competitor vices, says Leader. This makes the vice more accurate for first operations and more repeatable for second operation work.
For further information www.leaderchuck.com

BRG dives into benefits of workholding

Just over three years ago, deep sea welder and fabricator Ben Goodwin gave up his dangerous day job to start BRG CNC Machining, a subcontract machine shop. The Market Weighton-based company was launched with a three-axis machining centre, but has now taken its next step, installing a DMG Mori NLX2500-700 turning centre with workholding equipment from Hainbuch.

“With regard to a new high-end turning centre, one key area of investment was the workholding solution for the main spindle: a Hainbuch Spanntop Nova Combi collet chuck,” states Goodwin.
Typical workflow on the DMG Mori NLX2500-700 involves the machining of a huge variety of components.
“This week, we are machining 48-off parts for the utilities sector; 68-off 35 mm diameter components for a rape seed
drill in the agriculture industry; and motorsport components that are an urgent requirement,” explains Goodwin. “To effectively machine the huge diversity of parts that any subcontract company faces, we had to
have a machine fitted with chucks that facilitate fast changeovers, with rigid and
high clamping forces.
“By way of example, we regularly machine 76 mm diameter parts from 304 stainless steel in batches of 100-off,” he adds. “Using the milling turret, we are rough milling the components with a Seco HF end mill at over 6000 mm/min, at a depth of 0.8 mm. Clamping the parts on less than 30 mm of material, the Spanntop is achieving clamping forces of over 3.5 MPa. In comparison, the hydraulic three-jaw chuck on the sub-spindle only attains a clamping force of 1.6 MPa. The result of the high clamping force is enhanced surface finish and extended tool life, which we are achieving while running the jobs at speeds and feeds faster than we ever could have imagined.”
For further information www.hainbuch.com

Clamping force verification made easy

Workholding equipment manufacturer OK-Vise has announced two new systems for checking how tightly a component has been clamped, mindful that during automated machining in particular, the verification of holding force has always been a challenge. The products are available in the UK through 1st MTA.

The accuracy of workpieces, especially those that are delicate or of thin-wall construction, can be adversely affected if the clamping pressure is too high. Conversely, if the grip is too weak, there is a possibility of the part becoming dislodged during machining, risking operator injury, machine damage, tool breakage and scrap.
During automated hydraulic clamping, oil pressure is easy to measure, but other variables can also influence clamping force. In manual clamping systems, straightforward torque measurement is often used, although the relationship between torque and actual clamping force can be inaccurate. As a result, the approach that OK-Vise has taken is to integrate clamping force measurements directly into the company’s modular Multi-Rail RM fixturing system.
An on-screen digital readout of clamping pressure enables the operator to verify that a hydraulically secured component is held correctly. If required, an optional SCADA system can collect information from several displays over a standard Modbus connection so that historical data can be viewed and adjustments made as necessary.
The system also allows the holding force of manually secured workpieces to be checked. Here, a visual red dot in a clamp module gradually fades to grey as a spanner is turned, showing when the holding force is correct. Various modules are available for different clamping pressures.
For further information www.1mta.com

Coupling firm finds productivity mate

When the KTR Group ordered new machine tools to reduce processing times, the power transmission specialist also opted for new workholding technology from Hainbuch. The Rheine, Germany facility of KTR was aiming to generate significant improvements in set-up times and the subsequent manufacturing process.
“Several machines were due to be replaced after reaching the limit of their service life,” explains production manager Günter Schleyer.

“Therefore, we re-examined the clamping requirements. The important questions for us were how to position ourselves in the future and how do we increase flexibility? Among other things, we use machine tools for both series runs and single-item production. Here we were at a crossroads. On one hand, we required a specialised series production solution and, on the other hand, we needed a fast, flexible cell for the single parts.”
The company took a Torok manual chuck with a base plate, a clamping head and a mandrel as part of a trial phase. For KTR, the overall time saving was extremely important.
Says Schleyer: “We needed to know how the system would perform under everyday conditions. We had questions like whether the Torok was rigid, and would it meet our practical requirements? Could we organise our set-up more efficiently? And of course, holding forces and repeatability were highly significant.
“Practical experience had shown us that conventional jaws were out of the question,” he continues. “For our coupling manufacturing, parts are machined at high cutting speeds. Cams and bores are milled and drilled, so we have a wide variety of chip shapes that must not impair the function of the clamping devices. Also, the solution should be practically self-cleaning. Needless to say, the implementation of the Torok manual chuck on one of the milling machines passed the test with flying colours. With these findings, the green light was given for working together with Hainbuch.”
For further information www.hainbuch.com

Fourth axis trunnion system from Midaco

Midaco Corporation, one of the key partners of Hyfore Workholding, made its EMO debut in Hanover during September, using the opportunity to introduce a new fourth-axis trunnion system for vertical and horizontal machining centres.

The trunnion system is aimed at subcontract or low-volume manufacturing environments, where easy and rapid access to a fourth axis for three-sided machining of workpieces is necessary but not permanent. To facilitate ‘all-around’ machining, the trunnion rotates through 360°. A ‘parked’ fourth axis can impair access to the total machining envelope, whereas with the Midaco unit it is completely removed, along with its docking unit.
Midaco’s trunnion system is supplied with a permanently wired, universal receiver that automatically engages with the chosen fourth-axis unit (not supplied).
“Innovative components such as this can really help productivity as the operator can effectively be working on two jobs at a time,” says Rob Beckett, workholding product manager for Hyfore. “Different workpieces are being machined while the set up for the next – possibly different – batch can be undertaken safely out of the machine. Therefore, the transition between machining two different jobs is virtually seamless.”
In addition to the trunnion system, Midaco featured one of its M3016FL manual pallet changers on the stand. Midaco products are available exclusively in the UK from Hyfore Workholding, which can undertake all of the engineering and installation either as a retrofit or as part of a new turnkey installation.
For further information www.hyfore.com