In
In recent years, machine shops have paid more attention to both material flows and the attachment of workpieces in their machine tool purchases.
Automatic pallet change is also being increasingly utilized more with vertical machine tools.
It is becoming more common to incorporate a pallet pool with the machine to carry out even long unmanned work cycles, and many within the industry are also considering when a full-blooded Flexible manufacturing system (FMS) system would be a sensible investment.
All of these technologies offer completely new possibilities with significant improvement in plant utilization and efficiency, but at the same time also place new demands upon the fixturing concept system used.
DENSITY OF PACKING OF WORKPIECES
As soon as NC machines hit the market, it was realized that due to their large size, the traditional machine vise is very rarely suitable for attaching batches larger than one piece.
The development of the low profile clamp at OK-VISE Oy in the early 1980s became intrinsic part in overcoming this problem and was quickly adopted industry wide. Thanks to its small size, the filling rate of the machine could be increased - in other words, the machine tool could accommodate more workpieces at a time. Typically, the workpiece setup is then in a matrix formation. As a result, the average workpiece loading, unloading and tool change times decreased radically.
Since then, in some applications, the priorities have continued to evolve, necessitating a parallel development in fixturing solutions to keep pace. For example with the advent and increasing use of four-axis machine tools, the workpiece can usually be completed with two set ups when traditionally 6 manual set ups were required (at worst). This has led to more and more four-axis machines clamping workpieces in a row instead of a traditional matrix typical in three-axis machining.
In five-axis machines, on the other hand, the goal is often to machine the workpiece from all possible directions. The simplest and most common way is to clamp one piece at a time to allow the spindle and tool to move freely, this in turn has also driven fixturing solution development. In most cases, however, two set ups are still required per finished workpiece.
Matrix – row – and single workpiece formations
SET UP CHANGE EVOLUTION
The FIXTURING CONCEPT product family, developed and manufactured by OK-VISE Oy, includes numerous fixturing components that can also be used to clamp very challenging parts.
The system is modular, and many pieces can be changed by moving the positioning elements. These include stopper modules, side guides, and riser blocks. The fixturing components are based on and evolved from the OK-VISE low profile clamps.
When the workpiece is complex in shape, dedicated fixturing must be used.
In this case, many machine shops consider that the most sensible option is to build a fixture on the plate and change the fixture with some manual quick-lock method or zero-point clamping, which can also be applied to a fully automated fixture change.
Generic purpose fixture vs. dedicated fixture
AUTOMATION
Increasingly the industry is moving towards unmanned production.
Today automation related to fixtures usually involves two approaches:
Either the fixture plate ( “fixture pallet” ) or workpiece clamping is automated. This changes also the way how raw material and unfinished goods are buffered for next work steps.
If an automated pallet change system is in use – like for machine pallets or zero-point plates – then the entire fixture is changed with the pallet. The workpieces in the fixtures are clamped to fixtures manually, eg during a day shift.
If the workpiece is unloaded and loaded automatically, for example with a robot, an automatic clamp is required, which historically has been operated mainly with hydraulics.
Automation is one of the priorities of OK-VISE Oy's development, and in 2022 we have been excited to introduce electrical clamping system, not only suitable for modern machine tool systems, but also enables completely new ways of changing setup and workpiece loading.
INTRODUCTION TO WORKHOLDING
For people who want to study basics of workholding in machining centers, we have made a video Workholding today - an introduction by OK-VISE
Generic-purpose or dedicated Fixture?
Generic-purpose components vs. dedicated fixturing
In most cases machining a workpiece requires more than one fixture.
The fixture for a specific workpiece and a specific machining operation can be built by using modules for generic-purpose fixturing or dedicated fixturing.
A dedicated fixture is workpiece-specific, whereas a system built of generic-purpose components can be set up for a variety of workpieces.
Fixture built from generic-purpose fixturing components
- Modular system
- Off-the shelve availability of modules
- Possible modifications can be limited to individual modules
- Setup change can be done moving the stop modules
Dedicated fixture
- Production cost is the lowest of all
- High design cost
- Longer delivery time
- Setup change must be done by changing the fixture
In addition to these extremes, many fixturing challenges can be solved using an innovative mix of dedicated and generic-purpose components
Fixture design instructions
For all of our systems one of the vital components in fixture design is placing of the modules in their optimal position in the fixture.
Normally the process for clamping one workpiece will be to:
- Place the stopper(s) on the fixture
- Place the workpiece against the stopper
- Place the clamp (with position Aopt) against the workpiece
- Place second stopper(s) against the opposing jaw of the clamp
Instructions for Blank System design
As in every OK-VISE Fixturing Concept system, the basic modules in the Blank System are clamp, stopper, side guide and riser block modules.
To resist the clamping and machining forces, a pocket should be machined to the blank plate. Pictures of the pockets are available in the installation instruction.
Basic principle
Following is an example of one possible way to design fixturing.
We are assuming here that both the workpiece and the machine tool have been already defined.
Once these initial parameters are set proceed as follows:
-Select the fixture plate thickness & material
*nb. Thickness from 28 to 50 mm is the norm
-Both Steel and aluminium plates are used.
*nb. When utilising aluminium always use threaded inserts to ensure reliable installation and clamp operation.
We at OK-vise suggest that it is desirable to consider using an example of fixturing sets at www.ok-vise.com, similar to when using OK-VISE Blank System Fixture sets
We recommend that particular attention is made when considering whether single-directional or dual-directional clamping is needed.
Should you require further technical support in this matter please do not hesitate to request assistance from ok-vise@ok-vise.com .
REFERENCE DESIGN
When you have found a suitable fixturing set (let's use SK-Z4 as an example) then begin placing the components on fixture plate.
CLAMP POSITIONING
When designing the clamping position, consider clamp module length A=Aopt.
Dimension Aopt is not given for each clamp. If it is not specified, an average of Amin and Amax,can be used.
Aopt = ( Amin + Amax) / 2
where
Amin = clamp module length in rest position
Amax = maximum length of clamp module (with "full stroke", without any workpiece)
in this example we use KCD-DS2 which has a plate KCD-R1-M, which lifts the clamp up from the fixture plate.
WORKPIECE(S)
In our reference we are using dual-directional clamping, so we have two workpieces : left and right from the clamp.
Please make the dimensioning using average workpiece dimension.
STOPPER(S)
Place the stoppers directly on the workpiece(s)
ENOUGH STROKE ?
-Please ensure that the biggest workpiece also fits into the fixture while loading ( then clamp length A=Amin ).
D > Amax + 2 x W
-Please ensure that there is enough stroke in the clamp so that the smallest workpiece also fits into the fixture while loading ( then clamp length A=Amin )
D < Amin + 2 x W
RISER BLOCKS / PARALLELS
Just like in our example, you may want to lift the workpiece from the fixture plate.
Then position some riser blocks under the workpiece(s), here we use KP-1
SIDE GUIDES
Side guides are used to make the positioning of the work piece easier and faster
If machining takes place from only one direction, then a fixed installation of side guides is used.
Here we use KG-1
REPEAT ?
A multitude of fixture sets can be placed on a fixture plate by copying the design.
DESIGN POCKETS
To find correct pocket design for each Blank System module please refer to document BlankInst
We recomend the pocket be made 0.1 mm larger than the modules to ensure ease of installation
Tips for product selection
Fixturing Concept principle
The OK-VISE Fixturing Concept features a range of components that are suitable for clamping different workpiece types, sizes and materials on all types of workholding platforms and machining centers.
The concept is based on the benefits of the OK-VISE low-profile clamp: adaptability to various workholding concepts, extreme clamping force, stability and small size.
All systems in the OK-VISE Fixturing Concept include the following modules
- Clamp modules based on OK-VISE low-profile clamp.
- Stop modules. Clamp presses the workpiece against stop modules, creating either friction or form closure to hold the workpiece while machining.
- Side guides. These enable easy loading of workpieces.
- Riser blocks / parallels. These are used to lift up the workpiece from fixture base.
All modules of the OK-VISE Fixturing Concept are reusable
Therefore, life cycle cost of OK-VISE modules is low so using OK-VISE is a step towards sustainable production.
Our Blank System is a system for building Dedicated Fixturing (workpiece-specific fixturing). Normally only one setup of one workpiece can be clamped with these fixtures.
A second option for fixturing is to use a Generic-Purpose workholding system. A generic purpose system easily adapts to various workpiece sizes, and the components of these systems can be reused and simply reconfigured for a variety of applications and workpieces.
Most fixturing cases can be built using both of these concepts.
OK-VISE Fixturing Concept
Based on OK-VISE Clamping Method
How to use Multi-Rail RM
Here you find information how to use Multi-Rail RM system.
Assembly on various platforms
Multi-Rail RM base rail can be installed on many different platform types.
When base rail is installed on grid platform M12 we recommended you to use 2 pcs of shoulder bolts OKSB12-45 in positioning holes and in remaining holes D912 M12 x 45 bolts, like descibed in Multi-Rail RM adapter sets.
When installed on blank plates please make threaded holes like described in Threads and positioning holes on the platforms.
We advice you to make 2 positioning holes with tread and remaining holes with thread only.
When assembled on T-slots assembly we recommended using M-T1 machining option and positionining keys, then base rail positionning is faster and easier. When rail is assembled parallel to T-slots please use standard DIN912 bolts and T-slot nuts. When rail is assembled 90 degrees to T-slot direction then use fastening clamp ICI-12 set with proper size T-slot nuts and DIN912 M12 size bolts.
Stoppers
Stoppers can replaced to documented position positioning be using the scale in the base rail and mark in the stopper. In most stopper types the bolts are tightened with 10 mm allen key to 100 Nm torgue.
Clamps
Clamps expand when tightening the bolt with allen key, tightening torque transforms to clamping force. Please remember that a stopper module is needed on both sided of any clamp module.
Parallels
This instruction shows how to install parallels with T-nut, like models RMP-1, RMP-1H8 and RMP-2.
There T-nut of the parallel goes into base rail-slot, and when parallel bolt is tightened the T-nut rotates clockwise in the rail..
Side guide
Side guide offset is adjusted using treaded rod and nut. When offset is right the nut is used for locking.Side guide type RMP-M1 is with magnet and RMP-1 with M6 screw.
Magnetic side guide its easy and fast to remove after workpiece has positioned.
Instructions
In "Instructions" you will find some generic information about the OK-VISE product families and information on how to use OK-VISE products
- Tips for product selection
- Fixturing Concept principle
- Wedgeman selection Tool: an easy start with OK-VISE Fixturing Concept
- Fixture design instructions
- How to use
Please note: If logging into OK-VISE Extranet with VIP-user or Distributor passwords you may also find some more detailed information.
Wedgeman - Fixturing set finder
OK-VISE has designed an easy selection tool to help customers select the most suitable fixturing system for their needs.
- Choose a workpiece design from the examples given.
- Choose the platform you are using. The most suitable component sets will be displayed.
- To compare the sets and to obtain more detailed information, please follow the links to the OK-VISE product information.
OK-Vise Extranet
The OK-Vise extranet contains information that is not (yet) intended for all customers (along with all the information on the public website www.ok-vise.com).
As a registered user your status is upgraded to "VIP_USER" or "DISTRIBUTOR" to access to more information available.
Some pages still can only be viewed only by those with the specific rights, but most of the technical information on the product pages is fully accessible for downloading (for example, 3D drawings of our products).
