Linear Motion Tips, a leading source for engineering and manufacturing information, provides engineers and industry experts with articles, tips and guides to assist in knowledge and job performance. The drive belt system and linear drives articles below can be used as a professional resource.

No-Drift Absolute Gaging Package from HEIDENHAIN

Schaumburg, Ill. –HEIDENHAIN Corporation announces that it has coupled the new ACANTO Absolute Length Gage with the established and versatile ND 2100G GAGE-CHEK metrology readouts. This gaging package is a great solution for many fixed gaging applications.

The HEIDENHAIN ACANTO Absolute Length Gage with EnDat 2.2 provides the benefits of an optical encoder and solves many of the problems of different length gages such as gage drift, linearity over the entire measuring range, or referencing upon startup. The ACANTO’s measuring principle is the measurement standard and does not drift over time nor does it require mastering. “Sweet spots” are nonexistent with the ACANTO as 2µm of accuracy are held throughout the entire measuring length. The new absolute technology, using EnDat 2.2, enables the ACANTO to know its position upon power up with no need to reference. The ACANTO comes in both spring operated and pneumatically operated models and is offered in 12mm and 30mm measuring lengths.

The HEIDENHAIN ND 2100G GAGE-CHEK will handle gaging and inspection tasks with ease, from simple pass/fail detection up to complex logic statements communicating to a PLC.  They can be configured for basic or advanced operations where inputs can be assigned and combined as desired, along with mathematical, trigonometric or statistical formulas.  This makes it possible to measure even complex dimensions such as thickness, flatness, volume and more.  Rapid acquisition of measurement data can monitor dynamic events such as the eccentricity of a rotating shaft.

The ND 2100G GAGE-CHEK now has a new color LED-lit display for displaying results numerically or graphically as a bar graph or dial indicator. The ND 2100G GAGE-CHEK can manage up to 100 parts, each with up to 16 visible measurement features and 16 hidden ones and can save thousands of data entry points for internal statistical process control (SPC) or export. User customization is easy with programmable soft and hot keys. Min/Max functions monitor and store data, and warning and tolerance limits can be set to each display value.

A new plug and play routine allows for smooth interfacing of the ACANTO and ND 2100G GAGE-CHEK. The ND 2100G GAGE-CHEK can interface with 1 to 8 ACANTO Gages and will be an effective solution for many gaging applications. The ND 2100G GAGE-CHEK will also accept any EnDat 2.2 encoders from HEIDENHAIN including linear, rotary, and angle.

For more information, visit www.heidenhain.us

Linear actuator for automation applications

PILine ultrasonic piezo drives offer an affordable alternative to electromagnetic linear motors and motor-leadscrew combinations when small dimensions and/or high speed are important.

With velocities of up to 200mm/s, these drives are fast, compact and readily integrated.
In addition, PIline motors are self-locking at rest with zero heat generation, eliminating the need for an additional motor brake.
PI’s M-272 is a linear actuator designed for automation applications based on a maintenance-free PILine ultrasonic ceramic motor.
The M-272 closed-loop linear drive combines motor, actuator, linear encoder, guiding system and brake functionality in a very compact package.

Due to the integrated guiding system, a payload can be easily attached to the drive rod of the M-272 drive and positioned precisely.
The M-272 features a maintenance-free ceramic linear motor, has travel range of 50mm and 5um resolution with integrated linear encoder.
It is self-locking at rest, with no need for external brakes and no energy consumption.

PILine piezo motors are based on a new, patented, ultrasonic drive principle developed by PI.

Through its contact with the ceramic friction bar (runner), the moving part of the mechanical system is pushed along.

With each oscillatory cycle, the mechanical system executes a minute step of only a few nanometers and the macroscopic result is smooth motion with a virtually unlimited travel range.

The piezo ceramic plate is preloaded against the runner and thus generates the holding force when the drive is at rest.

Its highly specialized DSP handles all of the motion properties typical for ultrasonic piezomotors, such as dynamic control parameter adaption.
Optimized settling behavior of the mechanics within 10s of milliseconds is achieved by automatically switching between gain-sets for dynamic and static operation.

Physik Instrumente
www.physikinstrumente.com

MTS Systems’ Sensors Division’s magnetostrictive sensors new alternative

MTS Systems’ Sensors Division’s magnetostrictive sensors now provide the performance level that make them preferable alternatives to linear encoders in certain applications. The sensors can be utilized as encoders because they offer the performance and reliability needed for dynamic closed-loop control. They provide continuous, precise position feedback that permits velocity and position-controlled movements at very high or very low speeds.

“Magnetostriction offers several benefits over other technologies to provide reliable and accurate positioning,” said Matt Hankinson, marketing manager, MTS Sensors.   ”One of the key benefits it offers over incremental linear encoders is inherent absolute positioning. If a linear encoder drops below a minimum speed, it will create a cogging effect that forces the amplifier to speed up until the next signal is received. The result is an uncontrolled jerky movement not acceptable in most of the low-speed applications.”

In addition, according to Hankinson, magnetostrictive position sensors do not have a maximum or minimum speed limitation because they are absolute position devices; they continue sampling absolute position at a fixed rate and resolution regardless of the application velocity.

Another benefit of absolute position sensors is that they eliminate the need for moving to a reference mark or home position after a power reset. At any point in time, the absolute position sensor can report where it is without requiring a movement. “Many applications are now moving beyond incremental encoders and are advancing to absolute position feedback for improved safety and productivity,” said Hankinson.

“Performance was also previously a factor in some cases,” he continued. “Optical linear encoders have a range of performance that at the upper end could achieve resolutions and accuracy that magnetostrictive sensors could not meet in the past. However, advancements in magnetostrictive technology over the years have now increased the overlap in performance so they now fit into applications that could previously only use linear encoders. ”

Magnetostrictive sensors provide precise, dynamic measurement of absolute position and velocities and are capable of measuring signals in the sub-millisecond range.  They can reach sub-micrometer resolutions which permits displacements at very low speeds of only 0.5 mm/s; measurement cycle times down to 100 microseconds to track fast motion; a linearity of <± 0.01% and typical repeatability of 2.5 microns. Real-time linearity correction is available to get measurement accuracy down to 20 micrometers or better.

Another advantage of magnetostrictive technology is that it is not sensitive to contamination in harsh environments. An optical encoder’s reading head, a piece of glass and a laser that’s counting the marks, can be contaminated by dust or oil, causing loss of the optical signal which means the reader is unable to count the marks.

The magnetostrictive sensor’s parts are enclosed within the sensor, and the magnet provides non-wear technology that ensures robustness of the sensor for the life of the equipment. Also, whereas magnetostrictive sensors have historically been used inside hydraulic cylinders in harsh environments and encoders were externally mounted on machine tools, magnetostrictive sensors are now available with many options for mounting on machine tools and offer many interfaces, such as an absolute SSI interface.

“There are still applications that are best suited for linear encoders because of specific requirements, but today’s magnetostrictive technology is increasingly meeting the needs of a wide range of applications and provides significant productivity and cost of ownership benefits,” said Hankinson.

MTS Systems
www.mtssensors.com

New IP67-Rated LMB-410 spar linear encoders from AMO Corporation

AMO Corporation is proud to launch the all-new IP67-rated LMB-410 spar linear encoders at the IMTS 2010 in Chicago.

Available through CNC Design Pty Ltd (www.cncdesign.com) – a Melbourne-based control and automation specialist, the new LMB-410 measuring scales feature a stainless steel carrier providing robust measuring/position feedback and performance comparable to linear optical encoders.

The LMB-410 spar linear encoders, which operate on an inductive scanning principle, are suitable for general purpose machines like medical equipment, printing equipment, machine tools and military/aerospace applications.

Their IP67 rating makes the measuring scales suited for contaminated or dirty environmental conditions such as fluid submersible applications.

LMB-410 spar linear encoders feature adhesive-free mounting spar with a snap cover, which eliminates concerns associated to spars becoming loose in oily surroundings. The encoders also offer a slim stainless steel carrier integrated to the machine with an interlocking snap cover and screws to secure the scale tape in position. The encoder head can be equipped with automatic wipers to clean the scale during operation. The auto offset and gain compensation of the encoder head also eliminates the need for a test box during setup stage. The encoders can operate in a temperature range from -10º C to +100º C for up to 30m length and ±3μm/m accuracy. These meet high-speed, vibration and high-shock specifications.

Any non-guided AMOSIN encoder head can also be used with LMB-100 or LMB-400 scale mounting version. The absence of any magnetic components in the inductive scanning system removes the need for electromagnetic interference. Thus, AMOSIN encoders have no machine backlash error or measurement hysteresis.

RSF Open Linear Encoder

A new open linear encoder (no housing on scale) equipped with a unique integrated mounting control is now available from RSF. Called the MS 25, this RSF encoder utlizes a tricolored LED directly at the reading head enabling the user to gage if the mounting and subsequent measurement readings are optimal. It is available in North America through parent company HEIDENHAIN Corporation. Common applications for open linear encoders are stages for medical and semiconductor machines, as well as miscellaneous metrology applications.

Open, non-contact linear encoders are increasingly being used in measurement applications that require higher traversing speeds and operating cycles, as well as lower mechanical backlash and zero frictional force induced by an encoder. The RSF MS 25 linear encoder fits this bill and offers permanent control of the scanning signals over the whole measuring length. The use of the tricolored LED allows for easy mounting since no test box or oscilloscope is needed, and is helpful for quick troubleshooting during operation.

The RSF MS 25 utlizes a unique single-field scanning principle which allows for high traversing speeds (up to 10 m/s), large mounting tolerances and insensitivity to contamination on the scale. Integrated into the head of the MS 25 encoder is a wide range of interpolation electronics enabling resolutions from 10 µm to 100 nm. Two end-of-travel optical switch signals are also available directly out of the reader head. The end travel signal locations can be easily set by the user.

The buyer can also choose from six mounting configurations for the graduation, as well as from various substrate options for the tape and carrier. And due to recent advancements in technology, all of these benefits are now available in a small package design.

RSF Elektronik
www.rsf.at

AMO Corporation’s new IP67-Rated LMB-410 Spar Linear Encoder

AMO Corporation (www.amo-inc.com) is proud to announce the release of the new IP67-rated LMB-410 Spar Linear Encoder, which will be spotlighted at the 2010 International Manufacturing Technology Show (IMTS) at McCormick Place, Chicago on September 13 to 18. The company’s stall will be found in Booth #E-5220 inside the Quality Assurance Pavilion located in the Lakeside Center (East) Building.

The new LMB-410 offers robust measuring/position feedback with IP-67 rating and performance similar to a linear optical encoder. The LMB-410, operating on an inductive scanning principle, is best suited for general purpose machines, such as medical equipment, printing equipment, machine tools and military/aerospace applications. Its IP67 rating makes the machine ideal for dirty or contaminated conditions including being fluid submersible.

Its adhesive-free mounting spar with a snap cover eliminates concerns related to adhesive-backed spars becoming loose in oily environments. Its encoder head is equipped with wipers to automatically clean spar scale during operation. The encoder head’s gain compensation and auto offset eliminate the need to use a test box during setup.

The LMB-410 is rated for operation that ranges from -40 to +120°C for any measuring length ± 5 micron/m linearity. The new encoder also meets high-shock, high-speed and vibration specifications.

Renishaw Helps Achieve High Accuracy Grinding for Giant Wind Turbine Bearings

KMT Lidköping (www.kmtgroup.com/lidkoping/) has unveiled its new hard-turning VTG4000 (Vertical Turning Grinding) machine that uses a combination of Renishaw SiGNUM optical angle and linear encoders to achieve the required accuracy, and Renishaw magnetic encoders placed on the exposed axes of the cutting heads.

“Our largest machine used to accommodate parts up to 600 mm diameter, but the VTG4000 can handle diameters in excess of 4000 mm, the size of the largest wind turbine bearings. This is hard turning and grinding which can be very demanding, and the positioning accuracy is very important, with a direct effect on the quality of the finished bearings. A standard size machine, using ballscrews on the axes, will manage to maintain a 3 µm form deviation, yet despite the considerable difference in relative size, the VTG4000 has been proven to achieve an exceptional form deviation of less than 1 µm, with feed resolution in 0.1 µm steps,” said Eive Johansson, Lidköping’s VTG Chief Designer.

“At the heart of a Lidköping machine are the linear slides. The combination of hydrostatic guideways, air seals and linear motors create a stiff, accurate and maintenance-free system. To achieve dynamic stiffness we need high gain and the gain is linked to the quality of the encoder scales. It also makes a big difference that the angle encoders have the scale integrated directly onto the ring,” he added.

Mr. Johansson first saw the Renishaw SiGNUM encoders during the EMO 2007 exhibition in Hannover, and then followed a period of rigorous testing by the company. As he explained: “The choice of Renishaw was easy; we compared different scales assembled on our reference slide and bought the one with the best performance. It was important that the linear encoders could be supplied in a continuous length of at least 4.5 m and SiGNUM is the easiest way to achieve this. The Renishaw encoders also give more resistance to dirt. We have now fitted Renishaw encoders to all four linear slides and as expected, we have had no problems!”

“The rotary table has the same design principle, with hydrostatic radial and axial bearings, air seals and torque motors for the drive. The same analysis was done, and the Renishaw SiGNUM angle encoders were chosen,” he added.

The Renishaw encoders have an integral patented set-up LED that speeds installation and eliminates the need for separate set-up equipment/complex external, or oscilloscopes.

“One of the best features of the Renishaw encoders is how easy they are to set-up,” Mr. Johansson said. “With the scale attached and the readhead approximately located the indicator lights make it very easy to see how well the two elements are aligned and then make the final adjustments.”

FASTRACK Linear Encoder System from Renishaw

Renishaw’s new FASTRACK linear encoder scale system brings high accuracy, stainless steel construction and quick, easy installation to large, sectional machines used in flat-panel display and photovoltaic manufacturing applications, as well as large CMMs that require removal of the scale for transit. Also ideal for linear motors with aluminum substrates, and applications where thermal expansion of the scale must be independent of the machine structure, or those involving dissimilar axis materials, the track-mounted scale can run across gaps up to 25 mm wide, while providing ± 5 µm/m accuracy.

The FASTRACK system consists of two miniature guide rails that secure low-profile scales (8 x 0.2 mm cross-section) while allowing them to freely expand at their own thermal expansion rate with almost zero hysteresis. The scale can be installed, removed and reinstalled as many times as required, and damaged scales can be pulled out of the guide rails and quickly replaced, even where access is limited, reducing machine downtime.

FASTRACK is available on reels for cut-to-length flexibility at the point of installation, allowing machine builders to minimize stock and lead-times. Generous tolerance makes measuring and cutting quick and easy. Easily installed, the self-adhesive guide rails feature integral pre-aligned sacrificial spacers which are removed after the rails are fitted to the axis. The scale is then fed in from either end and locked to the substrate at a single datum point anywhere along the axis using cyanoacrylate glue or a clamp.

Part of a modular solution, FASTRACK can be used with either the RTLC stainless steel incremental scale and super-compact TONiC readhead, or Renishaw’s new RESOLUTE linear absolute encoder and RTLA absolute scale. The encoders in both set-ups feature advanced optoelectronics with resolutions to 1 nm, low sub-divisional error (SDE) and very low jitter for smooth velocity control and rock-solid positional stability. For TONiC RTLC incremental scale installations, limit magnets and a reference mark selector are fitted to the FASTRACK and secured with a bolted clamp rather than using glue. The RTLC scale features multiple INTRAC reference marks at regular spacing.

The FASTRACK system is backed by Renishaw’s global sales and support network and, like the TONiC and RESOLUTE encoder systems, it is compliant with the WEEE and RoHS environmental standards.

Renishaw
www.renishaw.com/encoders

SICK STEGMANN Introduces TTK70 Motor Feedback System

DAYTON, OH – SICK STEGMANN, INC. introduces the TTK70 Motor Feedback System.  The TTK70 is an absolute, non-contact linear measuring system that delivers measuring lengths up to 4,000 mm, resolution of <1 μm and system accuracy of <10 μm, at operating speeds up to 10 m/s.  The result is precise and highly reliable absolute position determination for linear motors in a diverse range of applications.  The TTK70 motor feedback system is rated for operation in temperatures ranging from -30…+85°C.  It carries the CE mark and is RoHS compliant.

The TTK70 consists of a read head and a magnetic tape featuring a magnetic code that forms the measuring scale – 10 mm wide, and up to 4,000 mm long.  The code consists of an incremental and an absolute track (twin-track tape).  Absolute position values are calculated by the read head first detecting the absolute starting position during start-up of the linear motor.  All further positions of the drive are determined via the incremental position on the magnetic track, i.e. sine/cosine signals.  The values are transmitted via the HIPERFACE® interface to the evaluation electronics of the linear drive – a market-standard method of communication that, for the first time ever via the TTK70, is now available for linear measuring systems.  The result is an interface standard for all common servo drives, that covers all applications, with only one signal type.

The robust metal housing of the read head offers IP65 protection, has two mounting holes designed for high tightening torques and, even with the plug connection, is hardly bigger than a matchbox – making it the smallest system of its kind.  Inside, the TTK70 features the latest in sensor and evaluation technology.  The sensor PCB, which is aligned with the measuring plane, is equipped with Hall sensors on two parallel tracks.  When installed their placement coincides with the position of an incremental and an absolute track on the magnetic tape.

SICK-STEGMANN is currently the only supplier worldwide that is able to offer to drive manufacturers both rotary and linear motor feedback systems with an integrated HIPERFACE® interface, popular in applications such as erosion machines, handling systems in semiconductor production, automatic assembly and placement machines, vertical lifting systems, pick and place applications in electronic production, or the food industry.

SICK STEGMANN, INC.
www.stegmann.com

Kübler by TURCK Magnetic Linear Encoders

Minneapolis, MN — TURCK introduces a new line of Kübler by TURCK robust magnetic linear encoders. Utilizing A and B output voltage channels plus a periodic index with the corresponding inverted channels, these encoders achieve high accuracy in a broad range of linear motion applications. The T8.LI20 and T8.LI50 linear encoders are available with either a push-pull output or an RS422 interface and provide a voltage range from 4.8 to 30 VDC.

The linear encoders are used with magnetic bands that are attached to the mounting surface and protected by a stainless-steel cover. The encoder’s resolution is up to 5 µm with quadruple evaluation, and its repeat accuracy is +/- one increment with a measuring speed up to 82 feet per second, depending on the resolution.

Kübler by TURCK encoders use non-contact technology and can survive environments with high vibration (30g/10-2,000 Hz) and shock (500 g’s/1ms). The products can also be used outdoors, due to an IP 67 protection rating, wide temperature range and the weatherproof die-cast housing. The metal housing also offers improved shielding against electromagnetic interference.

A built-in LED provides a warning signal or an index pulse, allowing for simple set-up and diagnostics. Connections are made via a high-grade shielded PUR cable that is also suitable for cable track installations.

TURCK
www.turck.us

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