Most expensive CNC metalworking machines are purchased without fixtures to hold the workpiece(s). With today's sophisticated machines, making tool changes in fractions of a second, and cutting at speeds we once thought impossible, the speed and quality of part clamping is the next most important opportunity for time savings and productivity improvement.
The selection of any single brand of hydraulic clamp, as any other important decision, must be made from an informed, intelligent point of view. Your choice should be based on many factors influenced by your specific application. Other factors can be used for general comparison and are strong indicators of the overall quality of the brand selected. Before making any decision, we ask that you take time to compare product quality, product and information availability, technical support and service both before and after the sale. When you do, you'll find VektorFlo® Metric "head and shoulders" above the rest!
When we at Vektek made the decision to enter the Hydraulic Clamping market, we knew that another "me too" product would not succeed. Only a product of outstanding quality would be successful in this competitive field. Armed with this knowledge our team of engineers began an extensive product-development process. Exhaustive research, design, development, and testing yielded a unified product line all of which incorporate the following appropriate features:
Compare the durability and long life of our devices with that of our competitors. Prove it to yourself. We welcome any head-to-head "run-off".
Availability of Product and Information
If you see a product on this website, we try to have it in stock. Barring unforeseen large orders, we keep adequate shelf stock ready to ship small orders quickly. We can normally ship next day or same day if necessary to help you out of a difficult situation. Many VektorFlo® Metric devices are conveniently interchangeable with competitive devices. Please plan adequate lead times into your production schedule when ordering large quantities.
We take pride in the information we share with you, our customer. We have attempted to create a website that is easy to read, understand and use. You will find the website organized so that you can find specifications, dimensions and product-specific features without a lot of useless rhetoric. Should you need information not contained on this website, our Application Engineering Staff would be happy to answer your questions.
Service Before The Sale
Our unique blend of telemarketing, catalog, website and technical support is there for you when you need us, not when “we’re in the neighborhood.” Pick up the phone and call us toll free. We’ll do our best to answer your questions, solve your problems or just discuss your application at your convenience. There is no charge for this service, we’ll even pay for the call.
A typical customer finds that it goes like this:
Service After The Sale
Unlike some sales people, we don't and won't disappear after the sale. We want your fixture to work right the first time and keep on working. If it doesn't work CALL US, you'll find us ready to help. Outside the USA, when you dial +1-913-365-1045 you talk to us.
We want your business today, tomorrow and next year. We will continue to do what it takes to earn your respect and business.
Planning Your Power Workholding System ...
Successful powered workholding does not just happen. Like any other manufacturing process, it must be carefully planned. But, that does not mean that you need to be a hydraulics engineer to implement a powered workholding system. Designing a system involves nothing more than the common-sense application of a few basic workholding concepts.
Applications for power workholding fall into two categories: retrofits to replace and upgrade clamping on existing fixtures and new fixtures designed from the outset with power workholding. In both cases, it is imperative that you keep in mind the forces that can be generated by power workholding devices. A single device, small enough to hold in your hand, can generate five tons of clamping force. If you are replacing existing manual bolt and nut clamping or toggle clamps, make sure that the fixture or machine tool base will withstand the forces. Don't risk damaging machine bed because you tried to tie a 30 kN clamp into a T-slot that would only withstand 15 kN of force.
Using power workholding does not in any way invalidate the principles of sound fixture design. The 3-2-1 concept as it relates to the location of the workpiece in the three planes is just as applicable when using power workholding devices as when using manual methods. Workholding devices should be positioned in such a way as to ensure firm contact between the workpiece and locating buttons, pins, or surfaces.
Begin the planning process by asking yourself the following: What do you want your system to accomplish? What sort of operation is going to use this system? What clamping "speed" is appropriate for the speed at which your production line runs?
You should select "realistic" cycle times ... the shorter the cycle time, the larger the power source you will require. For example, a pump with a 1/3-hp electric motor may be satisfactory to reach clamping pressure on a given system in three seconds. However, to accomplish the same task in one second may require a pump with a 1-hp electric motor - at a considerable increase in both initial expense and operating costs. So before you specify "instantaneous" cycling, be sure the increased clamping speed is really worth the higher costs for your particular installation. Ask yourself if you can productively utilize the seconds saved.
With this in mind, let's process step by step through a plan of attack for designing your system.
First, determine the nature of the operation to be performed, the number of parts to be processed per cycle, and whether operations will be performed on more than one surface of each part. Also, determine the time that should be allowed for loading, unloading, and clamping the part.
Consult your machine tool file to determine the available work space on the machine table, bed, chuck or another surface, as applicable. Be sure that the space available will accommodate the part or quantity of parts to be processed according to your manufacturing work-flow. If not, revise your plan.
In the initial phases of system planning, include adequate measures and devices to ensure the safety of workers and equipment. For more information, see the safety section.
Prepare an outline of the sequence of events that will take place during the manufacturing cycle. This will assist you in determining the types of special sequencing valves that you might need, as well as any external control (such as a tie-in with machine controls) that your application may require.
Calculate the cutting forces generated in the machining process and note the direction that these forces tend to act on the workpiece. If you are planning a retrofit of a manual clamping system, you may use the current torques. However, it is recommended that cutter forces be calculated as a precaution in such a case to ensure that workholding devices are sized to provide an adequate margin of safety. The operation manuals of many machine tools contain tables that list machining forces or simple formulas for calculating these forces. However, if you can't find the information, give us a call. We'll be glad to get you started.
Plan your fixture(s) with positive fixed stops to resist the majority of cutting forces and to ensure correct location of the workpiece using the primary part locating features.
Step 5: (Optional)
Normally, you need to calculate the forces required to overcome workpiece weight and friction and to move the part into position against fixture stops. However, with our systems, this is an optional step, thanks to the two-stage design of the VektorFlo® hydraulic power sources. The low-pressure high-flow first stage will move clamping devices into position around the workpiece and generate sufficient force to settle the workpiece against fixture stops before high-pressure clamping forces are generated. Additionally, in many applications, the nature of the fixture itself will ensure that the part is located closely enough to eliminate the need for positioning devices as a separate fixture element.
After you have determined the machine cutting forces, it is easy to calculate the clamping force required to hold the workpiece on the fixture or machine table. Again, a simple formula is all you need to arrive at an answer for the materials you'll be working with. Give us a call if you need help.
Determine where clamps should contact the part to hold or support it securely and to avoid interference with machine operations. If clamps cannot be located to avoid interference with manufacturing operations, it will be necessary to use an external control device to move the clamps out of the way as the need arises during the manufacturing sequence. This will require that electrically actuated valves be used to control the offending devices separately.
Determine the type and number of workholding devices you need based on the total clamping force required and clamping positions you've selected. Also, consider the size, strength and shape of the part, and the machine operation.
To help determine the capacity of the power source you'll need, add up the total oil displacement requirements for the devices you have selected. Then choose a power source with equal or greater capacity and determine if it operates the system within your clamping time constraints by working out the following formulas:
(Device cap.) ÷ (L. P. flow) = Position time
Where . . .
L.P. flow is low pressure pump oil volume expressed in cubic centimeters/minute. Device cap. is total device oil capacity expressed in cubic centimeters (cm3). Position time is time to position expressed in decimal parts of a minute.
To the result obtained above, add the result of the following calculation to rach the total estimated clamping time.
[(Sys. cap.) ÷ (H.P. flow)] x .01 (Sys. op. press ÷ 70) = Pressurize time
H.P. flow is high-pressure pump oil volume expressed in cm3 per minute. Sys. cap. is total system oil capacity, the workholding device capacity plus the internal volume of any associated tubing, hoses, manifolds, etc. (for small systems, the plumbing volume may be so small as to be negligible. However, for systems with long runs of tubing or hose, their volume may be of such magnitude as to materially affect the time it takes for operating pressure to be reached.) The expression .01 x (sys. op. pres. ÷ 70) takes into account the slight compressibility of oil and system elasticity which influence the length of time required to pressurize a system. Pressurize time is the total time to reach pressure expressed in decimal parts of a minute.
If total estimated clamping time is not within the cycle time requirements you've targeted but is within device limitations, a larger power source is required - one with greater capacity. Select such a source and repeat the above calculations to ensure that it will provide the clamping cycle times required.
If the total estimated clamping time in the initial calculation is significantly less than the time allowed, your initial power source selection may have been too large. In such a case, select a smaller power source and repeat the above calculations to ensure that it still provides the clamping cycle times desired.
Additional factors you should consider when selecting a power source include a shop floor plan and/or machine layout and your own preference for the type of power source (shop air vs. electric). If desired, large electrical power sources may be used to supply several workholding systems, each operating independently at several machines. In this case, the timing and sequence of operations for each system must be calculated as shown above in order to arrive at a size for the power source.
In Step 2 you outlined the sequence of operations desired. Now, select valves and
other control components that will support that sequencing. See the valve section for guidance.
Select appropriate safety controlled mechanisms. All VektorFlo® electrical power modules have a hydraulic pressure switch as standard equipment to ensure that consistent forces are maintained at all times. However, when a power source is used to power several separate individual systems, each system should also have its own pressure monitor.
Select the plumbing components required to connect the power source to the valves and devices. Review your system specifications and layout to determine what you need in terms of ratings, sizes, and lengths.
Call us for help. Our application engineers do not design fixtures. Their job is to help you use hydraulic clamps successfully. Whether you are retrofitting existing fixtures, need a concept for clamping a new part or want a quick review of your design. We stand ready to help VektorFlo® Metric customers.
Outside the USA,
Discover how easy, economical, and efficient power workholding can be - with one call. We'll be glad to answer your questions, provide concepts or advice, and give you a quote.
Frequently Asked Questions
This list of questions was developed by listening to customers just like you when they asked, "Why didn't I know that?" Before you order devices, build your fixture or even consider your design complete we suggest you run through this checklist to identify some common problems you might encounter.
Should I use or at least consider using double-acting cylinders?
Double-acting cylinders will assure full retraction on a timely basis even in systems where restrictions such as small orifices or long tubing runs have been introduced. The use of double-acting cylinders is especially important if "return" time is critical (as in some CNC controlled systems). We also recommend using double-acting cylinders in systems operating below 60 bar (6 MPa).
If single-acting cylinders must be used: Have I reduced the number of fittings (orifices), length of tubing and restrictions as much as possible? Are all of these properly sized?
Some fittings and hoses which are locally available (not from Vektek) have extremely small orifices, which restrict the flow. The use of G1/8 or similar size fittings can have this effect on a system. This restriction is even more pronounced when introduced at a main feed line. This can happen with some fittings and many hoses.
Excessive tubing length can create a very long column of oil. Friction created by moving oil will slow response times because of the inertia of the column of oil and increased back pressure of the returning oil. If single-acting springs are all that is pushing this oil, the back pressure can become sufficient to stall the cylinder.
Proper sizing of fittings for main feed lines and device supply lines will normally be accomplished by using the appropriate VektorFlo® fluid distribution manifold. Device fittings are G1/4 or G1/8. Main feed lines should be at least 8mm to avoid restrictions.
Is my plumbing free of obstructions and contaminants?
Tubing must always be flushed after cutting. Even if not cut in your shop, it was cut before it came to you. Chips, burrs, dirt and other contaminants have collected inside your tubing and drilled passages. These contaminants can cut device seals, damage valve sealing surfaces, cause erratic operation and reduce service life if not cleaned prior to fixture start up.
The use of improper fittings can also cause obstructions and restrictions. Be sure you haven't created obstructions by using non-standard parts.
Is my pump of appropriate size? It is rated for _____l/min, or _____cm3 per minute. My devices require a total of _____cc of oil to actuate.
For most normal size fixtures, a pump rated over 8l/min. (liters per minute) is not recommended. If your pump is rated much more than 4l/min, call us, we'd rather give you sound advice now than have you damage clamps and have to sell you replacements. Be sure that you do not exceed the recommended flow rates for your system. If you aren't sure, ask us.
My pump runs continuously. Is it the right type of pump?
Call us. It can often be made to work. Some modifications will probably be necessary. If you have a VektorFlo® pump which runs continuously, call us immediately (they are not set up to run continuously).
I've been using a dump pump (builds to pressure, shuts off and releases pressure automatically). Is this pump suitable for workholding?
It can be. It will work if the circuitry is properly designed. It may depend on circuit modifications or a pallet decoupler to work as required.
I want to make a cut directly against (into) a clamp. Is this possible?
Yes, it is but it will require special design considerations. We encourage that cutter forces always be directed toward a fixed stop. A fixed stop is designed to prevent part movement. A clamp is designed to position and force a part against a fixed stop. In order to machine "into" a clamp, the clamp must be sufficiently sized to resist all cutter and machine forces or the part will tend to shift.
When I indicate my part, it bends when it is clamped. Why?
Clamps should be positioned directly opposite a fixed locator, hydraulic support or other supporting element. This element may be a part of the fixture, a solid portion of a rigid part or a properly sized floating locator such as a hydraulic work support. If your clamp is putting force into your part, which is not transmitted directly into a solid stop, it may distort the part. Clamping on draft angles or "mushrooming" the part with excessive force can also cause part distortion. Send us a print of your fixture design, we'll be pleased to evaluate and make suggestions.
I hold all four corners of my part on solid locators. When I unclamp the part it seems to "spring" back into a different shape. Why?
First, holding all four locating points in exactly the same plane on your fixture is virtually impossible. (See your favorite text on fixture design for an explanation of 3-2-1 principles.) Second, because your part can't have all four of these points in the same plane, your part is distorting when clamped. Other factors such as stress relief may cause the part to change its "free" shape after machining.
My pump turns on and off approximately every 3-5 seconds. Why?
There could be several causes: A "spool" valve when used with a demand pump will cause it to turn on and off as its internal leakage bleeds off pressure. Use of spool valves voids warranties on VektorFlo® pumps. We suggest the use of "zero leak" poppet or shear-seal type valves.
Industrial type double-acting cylinders (even high-quality ones not designed for clamping) have significant leakage across their internal seals. This leakage will not normally be externally visible. Internal leaks from one side of the piston to the other will cause pumps to cycle excessively.
Note: These cylinders should be avoided in all palletized applications as they may cause pressure loss or back pressure at disconnect.
All leaks at fittings, seals or other typical leak points will eventually cause a pump to cycle. If your VektorFlo® pump cycles more often than you feel appropriate (more than once per minute without a valve being shifted) call us. We will gladly offer advice.
I want to limit the pressure into a sequenced hydraulic circuit. Which valve would I install first?
We recommend that you avoid putting one special function valve behind another if possible. If you must, put the pressure limiting valve after the sequence valve. This avoids the limiting valve being shut off before the sequenced circuit is fully actuated.
I want several sequenced operations to happen on my fixture. Can I put three or four sequence valves in series?
We do not recommend it. Our sequence valves operate better if run directly from the main hydraulic supply line and set at different pressures. (We recommend at least 35 bar (3.5 MPa) differential.)
My company uses a lot of brass fittings on our product. Can I use these to connect my hydraulic clamps?
No, brass fittings and some aluminum or steel fittings are for low pressures. Be sure that locally sourced fittings are rated for 350 bar (35 MPa) operation. We do not recommend the use of lower pressure fittings. Ask our local source for high pressure BSPP S-Series fittings.
I need to disconnect my fixture from the pump. I also need double acting clamps. How can I do this?
Our pallet connector was designed with a double-acting port incorporated. You can add a second quick disconnect (we suggest a female) to this port, and connect another line with appropriate valves. This is an exclusive feature of the VektorFlo® Pallet Decoupler.
We run a fixture for 3 months, store it for 6 months, then bring it back on line. How can we keep everything working?
Preventive Maintenance: Before you store your fixtures, be sure that they are free of coolants, coolant buildup, clean and dry. A light coating of corrosion protection may help. Be sure to store in a cool, dry, clean environment. We encourage the use of double acting clamps on fixtures that will be stored for extended periods.
Our clamps are used for cast iron grinding. Our coolants also seem to be corrosive (our fixture plates rust). Will your clamps stand up to this?
Nothing is going to be 100% foolproof. Our extensive use of hard chrome plating, stainless steel and our corrosion-resistant BHC™ will give you the best possible resistance to corrosion. Our processes will allow our clamps to run longer with fewer problems even in this destructive environment.
When I unclamp my single-acting clamps, a small amount of coolant comes out of the vent port. I am running flood coolant, and the clamps are covered during the entire machine cycle. Can I eliminate this problem?
Maybe. We suggest you run a vent line to fresh air from each breather port. This can be done in copper or plastic tubing. If you can't get to fresh air, a trap in the tubing or a protected vent inlet area will reduce the amount of coolant entering the cylinders. Keeping the coolant out will reduce the chance of corrosion in the cylinders. It will also keep the cylinders from having to expel the coolant that causes sluggish return. Our swing clamps are now available with bottom venting to allow them to breathe dry air from protected areas under the fixture.
When I look at my clamps, there are threaded holes in them. What do the labels "P" "ADVANCE" "RETRACT" mean?
These threaded holes are called ports. The label "P" or "ADVANCE" ports are normally used to clamp the part, "RETRACT" indicates the port normally used to unclamp or retract the clamp.
My local chemical representative has recommended the use of "water-glycol" hydraulic fluid. What are the benefits of this fluid and should I use it?
Water-glycol is a nontraditional hydraulic fluid. This fluid was developed for use where petroleum-based fluids are not allowed. They are commonly used in areas requiring "flameproof" fluid. They often cause problems with device seals, valves and pumps. We do not recommend water-glycol fluids. We may in some cases be able to provide devices with seal compounds acceptable for use in this environment. We cannot recommend or warrant their use in any Vektek pump or directional control valve.
What about using seals made of Viton®?
Seals made of fluorocarbon, such as Viton® can be a good answer for high heat applications up to 178°C, however, fluid type is also important. It may be acceptable in most fluids at lower pressures, but fluorocarbon is not a universal remedy for all fluid problems. There are other acceptable seal compounds for use in water-glycol and other unusual fluids. Our staff can help direct you to a seal that is best suited to perform in your application. Because seals made of fluorocarbon may work in your application, we offer this as an option on many of our cylinders, call for details.
How hot is too hot to run hydraulic fluid?
Anything above 177°C is considered too hot for most hydraulic fluids and seals. Our standard seals are rated to operate at temperatures from 4°C to 71°C. Even seals made of Viton® (fluorocarbon) are not recommended above 177°C. For advice on high-heat applications, you may contact Vektek's Engineering Department.
I have my cylinder hooked up to a pump. It extended but won't retract. What have I done wrong?
If there is not a directional control valve in the circuit, one is required. Is the cylinder single or double-acting? Can you provide a schematic or simple hand sketch for us to troubleshoot? We are glad to help.
I want to run my clamps on air. I really don't need much force. Since these cylinders are being used as positioners, is it OK to use air?
Some of our cylinders, (but not work supports) can be run on air, others may be adapted. If air provides adequate force, and you are happy, so are we. In some cases straight-line cylinders and work supports have been run successfully using high pressure gas. Swing clamps may not be used on high pressure gas. Please call our factory for information on our pneumatic clamping line, specifically designed for workholding with shop air (available in inch measures only).
I need some type of retractable locator. After my part is loaded, I want it to "disappear." Do you have anything to do this?
Block pull cylinders or any double-acting cylinder may be used in this way. If a precise location is required, please be sure to use a guide bushing to provide more accurate location
How do I read my gauge and what does it mean?
First, release all pressure on the system. Check the gauge for proper operation. Check to be sure that the gauge is returning to "zero." Pressurize the system and read the gauge. The current reading from the gauge indicates the pressure your clamping system operates at when clamped unless there is a pressure limited circuit branch. (The entire system equalizes at this pressure. Δ P is negligible when under static clamping conditions.) To extend the life of Pressure Gauges, run your system at no more than 75% of the gauge scale.
I need a clamp just like your 41-5011-11, except with a 150mm long rod. Can you help me?
Maybe. We do entertain specials from time to time. Please ask us. We often find that "special" requests coincide with our ongoing new-product development. If you have a specific need, it is worth asking. We may decide to do your special as a development project. We may not be able to produce it (actually you may not want it) because of cost. It may be something we have done before and will be relatively easy.
The danger involved in using "specials" is that we do not stock replacements on custom parts. When your machine crashes (when, not if), and you need a rush spare, custom parts have to be made from scratch. You will need to order spares at the time of the original order. The cost of a single replacement on a complicated special can often be 5-10 times the cost paid in the beginning. A little foresight will be very beneficial if you must have a special.
Fixture Designed By: __________________________________
Fixture Built By: ______________________________________
Built For: __________________________________________
Fixture Serial # ______________________________________
1. All pressure gauges reading checked and verified at "0" operating pressure. ___ Yes ___ No
2. Main system operating pressure read from the gauge mounted on the clamping system pump ______ bar (MPa) or inlet air pressure from air gauge on boosters ______ bar (MPa), booster ratio ______:______.
3. Pump restart pressure checked. Pump restarts at ______ bar (MPa).
4. Fixture operating pressure read at fixture gauge ______bar (MPa), side A and ______bar (MPa), side B
5. Pressure limit circuits pressure checked:
Side A ______ bar (MPa) Components & location: _________________________________
Side B ______ bar (MPa) Components & location: _________________________________
6. Sequence operations set to:
7. Fittings checked, secure, no leaks, proper type, not restrictive. ______ Yes ______ No
8. Schematic diagram attached.
9. Bill of materials (hydraulic components) attached.
For troubleshooting assistance contact your Designer/Builder or, complete steps 1-9 above and fax this sheet with all additional pages to +1-816-364-0471. We are pleased to be of service.
© 1996 Vektek, Inc. This documentation sheet may be used to document fixtures built using VektorFlo® brand hydraulic clamps. This sheet is copyrighted material and remains the sole property of Vektek, Inc. The use of this documentation sheet in its original form or altered state to document fixtures with non-Vektek product is a violation of your assigned rights.
Directional Control Valves
Swing Clamp Arms/ Link Clamp Levers