CNC Machines Information

22 November 2010 - AMO Corporation has released the new IP67-rated LMB-410 spar linear encoder at the recently held IMTS 2010 in Chicago, US. The LMB-410 measuring scale comes with a stainless steel carrier, offering robust measuring/position feedback with IP-67 rating and performance similar to a linear optical encoder.

Available through Melbourne-based automation and control specialist CNC Design, the LMB-410, operating on an inductive scanning principle, is best suited for general purpose machines, such as machine tools, medical equipment, printing equipment, and military/aerospace applications. Its IP67 rating makes the scale ideal for dirty or contaminated conditions including being fluid submersible.

Available through Melbourne-based automation and control specialist CNC Design, the LMB-410, operating on an inductive scanning principle, is best suited for general purpose machines, such as machine tools, medical equipment, printing equipment, and military/aerospace applications. Its IP67 rating makes the scale ideal for dirty or contaminated conditions including being fluid submersible.

The LMB-410 is rated for operation that ranges from -10 to +100°C for up to 30-m measuring length and ± 3 μm/m accuracy. The new encoder also meets high-shock, high-speed and vibration specifications.

AMOSIN inductive measuring systems
Any non-guided AMOSIN encoder head can be used with any of the LMB-400 or LMB-100 scale mounting version. The AMOSIN inductive measuring systems are supplied in two principal versions: an open, non-contacting system, or as a guided, encapsulated system.

Operating entirely on an inductive basis, all AMOSIN systems achieve high precisions of up to +/- 3 μm/m, but are nevertheless very well able to resist environmental influences and extremely high resistance to shock and vibration.

The high precision is mainly due to the procedure used to manufacture the rigid steel measuring tape, and to the exceptionally high quality sensor signal, with deviations in the ideal sine wave down to < 0.1 % harmonic content, as a measure of the achievable interpolation precision within the grating pitch.

Inductive scanning – high protection class IP67
Reference marks can be integrated on the measuring tape, and are supplied with a single, multiple, or distance coded patterns. The purely inductive scanning allows for the high protection class IP67 where the operation of the systems is not affected by contamination and pollutants in the form of dust, smoke, or liquids. Optical encoders require a complicated mechanical encapsulating enclosure, are more susceptible to damage and hence commonly incorporate air purging to protect the optical scale – neither which are necessary with the AMOSIN encoders. As a result, AMOSIN encoders require much less maintenance than optical encoders.

Particularly noteworthy is the insensitivity from magnetic interference as there are no magnetic components in the purely inductive scanning and a completely different technology than magnetic encoders. As a result, AMOSIN encoders are not at all sensitive to electromagnetic interference of any kind and have no measurement hysteresis (machine backlash error).

The gradual evolution of the stem through finite element stress analysis (FEA) and real-world use can be clearly seen in all the little pockets and curves machined out of the 2014 alloy block.

We’ve certainly never had any issues, whatever bike we’ve used them on, from years of epics to a year in Whistler, and they’re within a whisker of the biggest block stems in terms of stiffness. The shorter downhill versions have slightly thicker walls for even more strength and stiffness.

Two well-buried opposed bolts close the 'shallow S' split at the back to reduce stress on lightweight steerer tubes. The four-bolt front plate can be switched to the super-cunning Hope light-mount one and there are loads of colour options.

Machining from billet and anodising (in black, red, blue, silver, gold or gunsmoke) is all done in-house in Lancashire for ultimate quality control. Add bonus features like colour-matched Hed Doctor steerer plugs, and you’ve got yourself the most versatile, high value stem around.
Manufacturers description
CNC machined aluminium handlebar stem. 3D machined pockets around steerer and 4 bolt front clamp. Available for standard and oversized handlebars.


http://www.bikeradar.com/gear

Compensating for Eccentric Loads during High Speed Machining
As part complexity and production demands continue to grow, demand for high-speed, multi-axis machine tools has never been higher. Because of this demand the market has been moving towards machine designs that achieve very rapid acceleration. In order to achieve the rapid acceleration required the use of direct drive motor technology has increased. High-power, rare-earth magnets in direct drive rotary motors and the use of low inertia rotary and linear motors have made top speeds and acceleration rates much higher than were possible even a couple years ago. Increasing the speeds and acceleration rates that the machine is capable of is important to improving productivity but in order to realize this increase - accuracy must be maintained.
The increase in acceleration has introduced additional challenges when trying to maintain part accuracy. One such challenge is the affect of an eccentric load located on the table. It is very common for a part and fixture mounted on the rotary table to be off-center. This results in an eccentric load on the table. When the rotary table with eccentric load is located on top of one of the linear axes there is an interactive force between these axes. When the rotary axis accelerates, there is a centrifugal force and reaction force due to the acceleration applied to the linear axis. The same is true of acceleration of the linear axis; interactive force is applied to the rotary axis during acc/dec of the linear axes. The interaction between axes can be seen as a reduction in accuracy - in the form of a tool mark, step or oscillation at the tool tip. This is especially troublesome during 5-axis, high-speed machining cycles.

Interactive force is not easily compensated due to the variable nature load and speed. The only mechanical solution is to center the load on the table; this is not always practical. The other solution would be to reduce the feeds and speeds of the cutting cycle but at the expense of productivity. A better solution is to apply compensation in the servo system.
Interactive Force Compensation
The servo system of a FANUC 30/31/32i-A CNC (series 30i) is able to control up to 32 servo axes simultaneously via the FANUC serial servo bus (FSSB). This high-speed fiber optic communication means that all servo data and control loops are closed in the CNC at extremely high speed. This highspeed communication allows for compensation features not previously available. The recent addition of “Interactive Force Compensation” (IFC) addresses the problem of force interaction between linear and rotary axes. Once setup IFC enables highly accurate positioning control by compensating for mutual interactive force between axes in the servo software. The effect of this function is easily seen by improved speed and accuracy in 5-axis machining.

IFC is a standard feature on the series 30i CNC that only requires parameter setup and tuning utilizing FANUC Servo Guide PC based servo-tuning software. Various axis configurations are supported including; single rotary-to-linear interaction, rotary-to-rotary interaction, tandem/synchronous axes and compound axes. It is also possible to set IFC such that the interactive force between two axes can be compensated for each. This way the force from acceleration of a linear axis to a rotary is compensated and also the force due to acceleration of the same rotary to the linear can be compensated.

Interactive Force Compensation Example
IFC requires proper parameter settings of relationship between “moving axis” and “compensated axis” according to the actual mechanical configuration. In this example the machine has three axes for which compensation will be set. The rotary table sits on top of a compound X-Y linear axis.

* C axis (rotary axis) that has an eccentric load mounted on X axis (linear axis), and X axis is mounted on Y axis (linear axis).
* There is no interactive force between the X and Y axis, because X axis is orthogonal to Y axis.
* Not only are the interactive force from C axis to X- and Y-axis compensated but also interactive force from X- and Y-axis to C axis is also compensated.
Tuning for Interactive Force
Interactive Force Compensation requires some servo parameter tuning. This is due to the fact that the amplitude of force changes according to the position of the eccentric load on the table and the effect of the force differs between mechanical systems and axis arrangements. Because of the individual nature of the forces on a particular machine an angular offset and compensation gain must be tuned using PC based Servo Guide tuning software.

* At the point A and C in the figure, no interactive force acts on rotary axis as the linear axis accelerates.
* At the point A and C in the figure, interactive force which is produced by acceleration of rotary axis does not act on the linear axis, but interactive force which is produced by centrifugal force of rotary axis acts on the linear axis.
* At the point B and D in the figure, interactive force that is produced by centrifugal force of rotary axis is traverse to the linear axis and does not act on linear axis, but interactive force that is produced by acceleration of rotary axis acts on linear axis.
Effect of Interactive Force Compensation
The result of acceleration and centrifugal forces from the moving axis are seen as a position deviation in the compensated axis. Once the tuning of the angular data and compensation gain is completed IFC will eliminate the effect of interactive force on the compensated axis. A significant reduction in position error can be seen resulting in better part accuracy, reduction in tool marks and reduced chatter.

During high-speed machining utilizing both rotary and linear axes an eccentric load can result in significant position error due to the interactive forces. The centrifugal force and acceleration force applied is not easily compensated in a conventional CNC machine – typically, these forces limit the speed and accuracy. FANUC has developed Interactive Force Compensation as a means of reducing position error due to eccentric loads during high-speed machining, expanding the limits by allowing for higher production rates and better accuracy from high speed and 5-axis machining systems.


http://www.americanmachinist.com/304/Issue/Article/False/83893/Issue

As part complexity and production demands continue to grow, demand for C axis (rotary axis) that has an eccentric load mounted on X axis (linear axis), and the X axis is mounted on Y axis (linear axis). There is no interactive force between the X and Y axes because the X axis is orthogonal to the Y axis. Not only is the interactive force from C axis to X-and Y-axis compensated for, but also interactive force from X-and Y-axis to C axis is compensated. high-speed, multi-axis machine tools has never been higher.
Because of that demand, the market has been moving towards machine designs that achieve very rapid acceleration, and to achieve the rapid acceleration required, the use of direct drive motor technology has increased.
High-power, rare-earth magnets in direct drive rotary motors and the use of low inertia rotary and linear motors have made top speeds and acceleration rates much higher than were possible even a couple years ago.
Increasing the speeds and acceleration rates that the machine is capable of is important to improving productivity, but to realize that increase, accuracy must be maintained. The increase in acceleration has introduced additional challenges when trying to maintain part accuracy, and one such challenge is the affect of an eccentric load located on the table.
It is very common for a part and fixture mounted on the rotary table to be off-center.
That results in an eccentric load on the table. When the rotary table with an eccentric load is located on top of one of the linear axes, there is an interactive force between the axes, and when the rotary axis accelerates, there is a centrifugal force and reaction force due to the acceleration applied to the linear axis.
The same is true of acceleration of the linear axis. Interactive force is applied to the rotary axis during the acceleration/deceleration of the linear axes.
The interaction between axes can be seen as a reduction in accuracy — in the form of a tool mark, step or oscillation at the tool tip.
That is especially troublesome during 5-axis, high-speed machining cycles.
In the above example, the machine has three axes for which compensation will be set.
The rotary table sits on top of a compound X-Y linear axis.
The C axis (rotary axis) that has an eccentric load is mounted on the X axis (linear axis), and the X axis is mounted on the Y axis (linear axis).
There is no interactive force between the X and Y axes, because X axis is orthogonal to Y axis.
Not only is the interactive force from C axis to X- and Y-axis compensated but also interactive force from X- and Y-axis to C axis is also compensated.
-------------------------------------------------------------------------------- Interactive force is not easily compensated due to the variable nature load and speed. The only mechanical solution is to center the load on the table, and that is not always practical. Another solution is to reduce the feeds and speeds of the cutting cycle but at the expense of productivity.
A better solution is to apply compensation in the servo system.
Interactive Force CompensationThe servo system of a Fanuc 30/31/32i-A CNC (series 30i) is able to control up to 32 servo axes simultaneously via the Fanuc serial servo bus (FSSB). This high-speed fiber optic communication means that all servo data and control loops are closed in the CNC at extremely high speed.
That high speed communication allows for compensation features not previously available.
The recent addition of “Interactive Force Compensation” (IFC) addresses the problem of force interaction between linear and rotary axes.
Once setup, interactive force compensation enables highly accurate positioning control by compensating for mutual interactive force between axes in the servo software.
The effect of this function is seen by improved speed and accuracy in 5-axis machining.
Interactive force compensation is a standard feature on Fanuc’s series 30i CNC, and requires only parameter setup and tuning with Fanuc’s Servo Guide PC-based servo-tuning software.
Various axis configurations are supported, including single rotaryto- linear interaction, rotary-to-rotary interaction, tandem/synchronous axes and compound axes.
It is also possible to set interactive force compensation such that the interactive force between two axes can be compensated for each.
This way the force from acceleration of a linear axis to a rotary is
compensated, and the force due to acceleration of the same rotary to the linear also can be compensated.
Interactive force compensation requires proper parameter settings of the relationship between “moving axis” and “compensated axis” according to the actual mechanical configuration.
Tuning for Interactive ForceInteractive Force Compensation requires some servo parameter tuning. That is due to the fact that the amplitude of force changes according to the position of the eccentric load on the table, and the effect of the force differs between mechanical systems and axis arrangements.
Because of the individual nature of the forces on a particular machine, an angular offset and compensation gain must be tuned using PC based Servo Guide tuning software.
Effect of Interactive Force CompensationThe result of acceleration and centrifugal forces from the moving axis are seen as a position deviation in the compensated axis.
Once the tuning of the angular data and compensation gain is completed, interactive force compensation will eliminate the effect of interactive force on the compensated axis.
During high-speed machining utilizing both rotary and linear axes with an eccentric load can result in significant position error due to the interactive forces.
The centrifugal force and acceleration force applied is not easily compensated in a conventional CNC machine – typically, these forces limit the speed and accuracy.
Fanuc has developed Interactive Force Compensation as a means of reducing position error due to eccentric loads during high-speed machining, expanding the limits by allowing for higher production rates and better accuracy from high speed and 5-axis machining systems.
http://www.americanmachinist.com/Classes/Article/ArticleDraw.aspx