|
|
 |
|
|
In Focus - Archives Novembre 2008
|
| |
|
|
|
Pneumatics : Approved
|
 |
Compact, attractively priced, universally applicable. The JGP pneumatic gripper is an economical all-rounder with an outstanding price/performance ratio.
|
|
|
01.11.2008 -
Pneumatic drives for grippers, linear axes or swivel units represent a technology that was introduced successfully decades ago and has proven its effectiveness. The necessary air pressure infrastructure usually already exists in the company, and pneumatic drives are characterized by good dynamic, force and torque values. Pneumatic drives are not overcomplicated in terms of technology, and therefore are usually inexpensive. This means the associated fixed costs are comparatively low. For example, small grippers in particular are less expensive than their electrical counterparts.
However, pneumatic drives offer fewer control possibilities, because a pneumatic component is usually only capable of performing a movement in full or not at all. Intermediate positions can only be achieved using considerable complexity, and it is practically impossible to influence parameters such as the speed profile of a movement.
The compressed air required by pneumatic drives is a very expensive form of energy and its overall costs are frequently underestimated: Depending on the factors taken into account, it can be 4 to 7 Euro cents per standard cubic meter. In addition, pneumatics require a complicated infrastructure which includes compressors, pipes, drying systems, oilers and filters. This means that although pneumatics have lower fixed costs, the variable costs are also higher. This means the total cost of ownership rises significantly as the cycle counts go up.
|
|
Mechatronics: Flexible
|
 |
|
Ground-breaking: The mechatronic SDH-2 from SCHUNK makes innumerable gripper variants possible. It has three identical fingers, two of which can even be rotated. Tactile sensors additionally ensure a sensitive and, at the same time, secure grip.
|
|
|
Mechatronic components are driven electrically, mostly by means of a servomotor which forms the mechatronic unit in conjunction with an integrated controller.
Mechatronic drives make it possible for almost all parameters of the movement to be controlled. Both force and position-controlled movements are possible, the position is always known even without additional sensors, and path control is also possible when several modules are linked together. This means movements can be performed along paths of any shape with freely selectable speeds.
For electrical gripper systems, for example, these characteristics mean it is possible to monitor parameters such as gripper positions, strokes, closing speeds, accelerations or forces accurately. Measuring movement and holding currents provides information about current accelerations and forces, and therefore mechatronic grippers deliver data that can be processed in the machine controller or in an external computer, even without additional sensors. All parameters can be interrogated at any time, therefore production processes can be monitored more easily – even at any distance.
The actual values of the various parameters can be changed within an extremely short time by the controller, and therefore production can be made much more flexible than ever before. Whereas pneumatic grippers can only be opened and closed, their mechatronic counterparts offer quite different possibilities. For example, if a stroke of only two millimeters is required for a gripping process, then a pneumatic gripper with a fixed stroke of 20 millimeters cannot be adapted to this: The gripper has to open completely in every cycle, something which not only takes time but also consumes compressed air. By adapting the fingers to the diameter of the workpiece, it is indeed possible to limit the stroke. However, grippers adapted in this way are then only suitable for this one workpiece diameter and have to be changed if there is a product change.
In an electrical gripper, the stroke can be set to very small values by positioning the gripper fingers in advance. This reduces the closing and opening times as well as the cycle times – above all these settings can be adapted to different workpiece diameters at any time when there is a product change.
Mechatronic systems offer their users many new possibilities, but this is precisely why they are significantly more complex than pneumatic systems. The use of mechatronics therefore represents a new challenge for many companies. Employees in design, production and sales have to tread a new technical path and need to be provided with new skills for this purpose.
|
|
Clear result in the cost comparison
|
|
Pneumatic systems are regarded as relatively attractive in terms of pricing, and indeed pneumatic components are usually less expensive to purchase than mechatronic components are.
However, all too frequently the total costs are not adequately taken into account when procuring machines and components – and this error can prove to be a very costly one in times of high energy costs.
This is because a comparison of the actual total costs which also include the expenditure for operation, startup, maintenance, etc. reveals that the apparent cost advantage of pneumatic systems is in fact an illusion. Prof. Dr.-Ing. Wolf-Dieter Goedecke from the Schunk cooperation partner GAS has carried out a comparison between pneumatic and mechatronic drives for linear axes, and his results are clear.
As shown in the table below, pneumatically driven linear axes may in fact be somewhat cheaper to purchase but their total costs are far higher. The comparison between energy costs during operation is striking: because compressed air as the energy type is significantly more expensive than electricity, the energy costs after five years with pneumatic axes are on average about 20 times higher than electrically operated axes.
|
 |
Article "Vergleich servopneumatischer und servoelektrischer Linearachsen" in O + P magazin for fluidic technology 48 (2004), Nr. 4 - April/May 2004.
Authors: Prof. Dr. Ing. Wolf-Dieter Goedecke, Dipl. Ing. Volker Langguth
|
|
 |
|
The LEG lightweight gripper with a modular structure can be configured in many different ways. Users can even select between a pneumatic and electric drive.
|
|
|
SCHUNK has prepared a comparative calculation for grippers that revealed similar results. A comparison between the LEG electrically driven packaging gripper and its pneumatic counterpart the PFH shows that the LEG will have made good its significantly higher initial costs after an operating period of 2 years, and from then on continues to deliver cost advantages.
|
|
Summary
|
 |
|
Synergy of pneumatics and mechatronics: In the SRU-MD swivel unit from SCHUNK, the high dynamic values and quick response of an electric motor are combined with the power density and strength of a pneumatic drive to make a force package that is fast and can cope with twice the level of load.
|
|
|
Mechatronic systems offer a range of additional advantages compared to pneumatic drives. Their flexibility opens up new possibilities for designing handling and assembly processes, and their overall business costs make them the clear leader in terms of cost benefits. Pneumatic grippers, on the other hand, are attractive when it comes to the initial purchase price. They are straightforward to start up, robust and easy to understand, and many companies have gathered decades of experience with them.
It does not exist a clearly "Right" or "Wrong" for the decision between both systems. The crucial factor will be the on-site situation which should be analyzed very carefully under consideration of all factors of influence.
|
|
| |
|
| |
|
|
|
| |
|
|
12.2008
Quick jaw change brings flexibility and substantial savings
Flexibility in production is a crucial competitive advantage. Only companies that can respond to demand with flexible yet absolutely precise production can supply their customers rapidly with a constantly increasing variety of products without needing to build up expensive and inefficient stocks.
 Pour en savoir plus…
|
| |
|
|
11.2008
Pneumatics or mechatronics? … It all depends!
To date, pneumatically driven gripper modules have been used primarily in gripper technology. Recently, however, more and more electric grippers have been coming onto the market. Both competing systems have powerful arguments in their favor.
Pour en savoir plus…
|
| |
|
|
10.2008
High-Performance-Cutting (HPC)
Hard on the outside, clever on the inside: Toolholder systems developed especially for HPC that have strong rigidity as well as good vibration dampening provide clear benefits for HPC.
Pour en savoir plus…
|
| |
|
|
09.2008
Cleanroom
The importance and the use of cleanrooms in assembly and handling are constantly increasing.
Pour en savoir plus…
|
| |
|
|
08.2008
Clamping Force / Torque
We are frequently confronted with torques on a daily basis, even though we do not recognize them as such.
Pour en savoir plus…
|
| |
|
|
07.2008
Convenient robot or attractively priced spindle gripper?
A significant potential for increasing efficiency in modern machining processes is the automated loading and unloading of the machines.
Pour en savoir plus…
|
| |
|
|
06.2008
Polygon clamping technology - round pegs in polygonal holes
The principle behind polygon clamping is surprisingly simple. The know-how that makes it work is however highly advanced.
Pour en savoir plus…
|
| |
|
|
05.2008
Packaging
A package for everything
Packaging is a universal function that is required in practically every industry and meanwhile is so important that it has become a separate industry itself.
Pour en savoir plus…
|
| |
|
|
04.2008
Magnetic clamping technology has strong attraction
Workpiece clamping with electroermanent magnets reduces set-up times by up to 50 percent and brings about significant advantages especially in the manufacture of large parts.
Pour en savoir plus…
|
| |
|
|
03.2008
Quick-change systems speed up production
Changing systems for components such as grippers and tools add a high degree of flexibility to production processes
Pour en savoir plus…
|
| |
|
|
02.2008
Vibration damping
Improves surface quality and reduces wear on the tool and spindle.
Pour en savoir plus…
|
| |
|
| |
|
|
|
| |
In Focus - 2013
In Focus - Archives 2012
In Focus - Archives 2011
In Focus - Archives 2010
In Focus - Archives 2009
In Focus - Archives 2008
In Focus - Archives 2007
|
|
