FAQ - Frequently Asked Questions on ForceCheck

ISO Steep Taper 10, 15, 20, and 25
CAT/ANSI/BT/DIN Steep Taper 30, 40, 45, 50, and 60 (more unusual BT sizes such as 35 are available as special order)
HSK 25, 32, 40, 50, 63, 80, 100, 125, and 160.
Capto/PSK C3, C4, C5, C6, C8, C10
KM 40, 6350, 50, 63, 80, 100

In addition, we can make special gauges for just about any spindle taper. Contact us for more information.

How do I justify the cost?

Catching just one drawbar problem before it damages the spindle taper can easily pay for the ForceCheck gauge. This does not take into account the costs of unexpected machine downtime while repairs are completed. Unfortunately, companies often only buy a gauge after they have had an expensive repair incident -- they want to be sure it doesn't happen again! We recommend being proactive -- the drawbar on your machine will fail at some point. It's better to know in advance that failure is coming, rather than having an unexpected failure in the middle of that critical job.

To what standards are ForceCheck gauges made?

We manufacture our machining center force sensing bars to tighter tolerances than called out in the standard for the tool holder–steep taper CAT/ANSI, BT, DIN, HSK taper, KM, and Capto.

What is your experience with power drawbars?

We are the US representative for BERG Spanntechnik, one of the premier manufacturers of power drawbar systems in the world. This gives us extensive expertise in the clamping system of machining centers that we have applied in designing the ForceCheck.

Who uses ForceCheck?

There are several thousand ForceCheck gauges in use all over the world. Most machine builders use our gauges as part of their quality control checks on new machines and many machine tool service companies rely on the gauge as well. Most major aerospace and automotive manufacturers have ForceChecks as well as manufacturers in medical and many other industries.

Does a certificate of accuracy come with the ForceCheck gauge?

Yes. All ForceCheck measuring bars are calibrated using a master that is certified using NIST traceable equipment.

How often should I calibrate?

We recommend every year but the frequency of use may require a shorter interval of time between calibrations.

Does the ForceCheck display require calibration?

No. Unlike other products, our unique at-the-sensor analog to digital conversion means that the ForceCheck display does not require calibration.

What units of measurement are available on the ForceCheck gauge?

The most common unit to measure force is the Newton (N or kN). Pound-force (lb-f, klb-f) and kilogram-force (kg-f) can be displayed as well. Some ForceCheck gauges provide measurement for RPM (revolutions per minute), torque, position, temperature, and others.

What is the ForceCheck measuring range?

The sensors in ForceCheck measuring bars are sized to match the typical force range for a taper. For example, our 30 steep taper measuring bars are designed to measure up to 15,000 N (approx. 3,500 lb-f), and our 50 taper up to 50,000 N (approx. 12,000 lb-f). A one-size-fits-all approach to the sensor doesn't work well for the large force range between different taper sizes (some competitive products use one sensor for all taper sizes, meaning the unit will not be very accurate for small taper sizes and may not be able to handle the force present on HSK100 machines).

How accurate is the ForceCheck gauge?

Under laboratory conditions, ForceCheck drawbar force measuring bars measure accurately within 0.5% (one-half of a percent) of full scale. Other sensor types such as chuck force gauges have different accuracies. Contact us for further information.

How repeatable is a ForceCheck gauge?

The ForceCheck gauge is also typically repeatable within 0.5% in our laboratory. However, in the "real world," when checking machines you will likely see more variation between readings because of differences in settling of the spring pack for each clamping cycle.

There is variation between drawbar force measurements on the same machine -- why is this?

There can be considerable variation in measured drawbar force between force measurements. We find this is typically about ±5%. Depending on the type of clamping system, components in the system, and other factors such as lubrication, force can vary by as much as ±10% in some cases.

This variation is caused by a number of factors but is primarily due to the mechanical components of the clamping system settling slightly differently each time the system is engaged. With most HSK grippers especially, there is normally a system of wedges that provide mechanical advantage. Between this wedge mechanism, springs, and other components there is considerable potential for variation.

Force measurement can be inconsistent between measurements as a result of the springs depending on the type of spring used. Standard tolerance Belleville springs and helical disk (Roehrs) springs will show the most variation between clamp cycles. A carefully engineered clamping system that uses tight-tolerance Belleville springs with specialized coatings will show very little variation between clamp cycles. In any case, one or more broken springs can cause considerable variation.

The amount of lubrication present in the gripper, drawbar, and other components can make a difference in repeatability. A freshly lubricated system will behave very differently than one that has been cycled a few times. To reduce this effect we recommend performing about 10 clamping cycles with a tool before measuring force on a freshly lubricated system. On the flip side, insufficient lubrication can cause erratic force measurements due to high friction between components.

It is important to remember, when checking drawbar force, the primary concern is a large change from manufacturer recommended force (we recommend greater than 20 or 30%, but you should consult the machine builder or spindle manufacturer to confirm what is appropriate for your machine/application), as well as trends (consistently dropping force from day to day or week to week). This is an indication that there is a problem with the clamping system.

What force should my drawbar have?

Force for a machine depends on the design of the clamping system. Determining what is the "correct" force is ultimately up to the machine builder, and is dependent on the purpose of the machine. For example, a machine designed for light-duty milling may have a lower drawbar force than one designed for heavy chip removal, even though the two machines use the identical tool taper.

As a guideline, we have put together this informational sheet.

How reliable is the ForceCheck gauge?

ForceCheck is very reliable. We believe the ForceCheck gauge is the most reliable gauge on the market. Our 10+ years experience of building the unit gives us a proven reliability track record. If our competitors tell you "sensitive electronic units" can easily be damaged, don't believe it. Ask them how often they get units back for repair –particularly hydraulic units.

Can you make "special" measuring bars?

Absolutely! We have our own force sensor installation lab so we can make a sensor for the ForceCheck to meet your specific application. If you would like to find out what forces are associated with a clamping system, improve reliability, or are interested in using force sensors for preventive maintenance please contact us.

Do I need to assemble pieces before checking the force on my machine?

No. ForceCheck measuring bars are completely integrated and only require the installation of a retention knob. Thre is no need to sort through a confusing set of tapers, spacers, and shaft parts to check a machine.

What languages are available on the gauge interface?

The ForceCheck gauge interface can easily be translated to any language on request.

I have an HSK-E or HSK-F taper machine -- are there any special considerations?

HSK forms E and F do not have "drive key" features. Sufficient drawbar force is especially critical for HSK-E and HSK-F taper machines because these tapers rely entirely on friction to prevent the tool from slipping. Low force can very quickly result in damage to the spindle taper and a very expensive repair bill.

Why would I want a wireless ForceCheck?

There are several cases where a wireless sensor is convenient or a must-have.

For very large machines, it may be difficult to be near the spindle and the machine control at the same time. Having a wireless sensor makes this easier. In addition, we offer sensors with a tool change groove which allows the sensor to be loaded through the tool changer.

If your company has a safety lock-out policy it may be difficult to gain access to the machine spindle for safety reasons. In this case, a sensor with a tool change groove can be loaded through the "approved" method (the tool changer). The force can then be read wirelessly without the need to do a safety lock-out on the machine.

The ForceCheck tablet display provides several functions that make machine record keeping much simpler. The tablet display is only compatible with wireless sensors.

Our chuck force sensors are available in both wired and wireless, but the wireless sensor allows the chuck holding force to be measured at speed. This is critical because force drops off considerably as RPM increases.

What are the advantages of ForceCheck over other gauges?

ForceCheck is more reliable, has higher accuracy, is simplistic in design and interface, portable, and has the availability and variety of custom features that can be installed with a gauge. Our support and professional expertise in the machine tool industry have also placed us on top of the market.

Gauge or gage?

Gauge more often refers to a measuring instrument but, technically speaking, both are correct. We use gauge because it is more accepted internationally (a lot of ForceChecks are sold internationally).

Where is ForceCheck made?

ForceCheck gauges are made in Rockford, Illinois, USA