Industrial Testing Equipment · Material Testing Machines
Screw torque tester with a cable-connected detector head, for checking the torque of screws already tightened, with peak hold, averaging and stored readings.
HDP-5 (4 models) ·
A driver’s clutch setting says what the tool was asked to do. The screw says what it received. Between the two sit thread friction, joint friction and the condition of the bit, and the only way to see the difference is to measure at the screw.
The instrument is in two parts: a display unit with the keys and the screen, and a detector head on a coiled cable. The head is fitted with a bit, engaged in the screw head and turned by hand. Everything the screw resists passes through the head, and the display holds the peak.
That arrangement is what makes the unit useful after assembly. The product does not have to be brought to a bench, and the driver does not have to be removed; the head reaches the screw where it sits, which is the only place a tightening torque can still be observed without disturbing it.
The detector head contains a strain-gauge element in the load path between the bit and the body of the head. Turning the head applies torque to the screw, the element strains, and the cable carries the signal to the display unit, which converts it to the selected unit.
PEAK holds the highest value reached. On a tightening check the screw is turned further and the peak is the torque at which it starts to move; on a loosening check the peak is the torque at which it breaks free. TRACK shows the signal live, which is how the instrument is zeroed and how a screw that is already stripping can be seen before the reading is taken.
The stored readings and the average are for sampling rather than for a single check. A batch is measured at several points, the readings are held and averaged, and the average is what gets written into the record.
Match the range to the screw, not to the driver. The torque that holds a small machine screw is a fraction of what a self-tapping screw in plastic takes, and a head chosen for the larger case will read the smaller one near the bottom of its scale.
Decide whether the check is destructive or not. A loosening check can be made on any assembled product but leaves the screw loosened; a tightening check has to be made before the screw is finally seated, which means it belongs on the line rather than at the end of the process.
Think about access. The head is a cylinder on a cable, and the cable has to reach the screw with the head square to it. A recessed screw or one behind an obstruction may need a bit extension, and the extension changes the reading by adding its own wind-up.
Then decide how the result is recorded. A single check needs the peak hold and the alarm; a sample that goes into a record needs the stores, the average and the interface.
The reading depends on the bit fit. A bit that is loose in the screw head takes up clearance before it turns the screw and reads low; one that is a tight fit but worn reads erratically. The bit is part of the measurement, not an accessory to it.
Loosening torque is not the torque that was applied. It includes the static friction that has to be broken, and it rises as the joint settles, so a screw measured a day after assembly reads higher than the same screw measured an hour after. Comparing readings taken at different intervals is comparing two different quantities.
Hand turning sets the rate, and the rate sets the peak on a screw that moves progressively. A fast turn reads higher than a slow one, so the same operator should take the sample, or the method should fix the speed.
For a screw that is still being driven, or for setting a driver’s clutch before assembly, a bench tester with a reaction head is the right instrument; this one assumes the screw is already in place and that the question is what it took.
Every value below is taken from source documentation. Where a parameter is not stated in the available material it is marked as information required rather than estimated.
| Range, HDP-5 and HDP-5S | 0.015 to 0.500 N·m / 0.15 to 5.00 kgf·cm / 0.15 to 4.45 lbf·inStandard |
|---|---|
| Range, HDP-50 and HDP-50S | 0.15 to 5.00 N·m / 1.5 to 50.0 kgf·cm / 1.5 to 45.0 lbf·inStandard |
| N·m row of the technical table | Printed as 0.015 to 0.500 for both size groups; the selection table gives 0.15 to 5.00 for the larger groupInformation required |
| Accuracy | ±1.0% with three digits, quoted inside the lower tenth of the rangeStandard |
| Measurement modes | TRACK for a live reading; PEAK for the held maximumStandard |
| Units | N·m, kgf·cm and lbf·in, three-position switchStandard |
| Direction | Clockwise and counter-clockwise, with the sign shownStandard |
| Reference standard | Not stated in the materialInformation required |
| Display | 2.8 inch colour LCD, two rows, for settings and resultsStandard |
|---|---|
| Keys | Power, function, set, print, reset, clear, unit, store, average, select and memory keysStandard |
| Stored readings | Ten readings held in memory and printableStandard |
| Stored settings | Ten numbered groups, recalled by numberStandard |
| Averaging | Mean of the stored readingsStandard |
| Alarm | Upper limit entered by key; the display shows the old and the new value while it is being setStandard |
| Auto power off | Five minutes without operationStandard |
| Supply | 1.2 V rechargeable cells, five of them, as printedStandard |
|---|---|
| Charging time | 6 hoursStandard |
| Charger | Input 220 to 240 V AC, output 7.2 V DC at 400 mAStandard |
| Battery life | Not stated in the materialInformation required |
| Construction | Two parts: a display unit and a detector head, joined by a coiled cableStandard |
|---|---|
| Display unit | 165 × 55 × 5 mm, 1.5 kgStandard |
| Display unit thickness | Printed as 5 mm, which is out of scale with the other two figuresInformation required |
| Detector head | 30 mm diameter, 150 mm long, 0.5 kgStandard |
| Bit fitting | Not stated in the materialInformation required |
| RS232 | Fitted, for recording and printingStandard |
|---|---|
| Command set | SCPI, for remote control and data collectionStandard |
| Standard accessory | LK26012Standard |
| Accessory content | Names, quantities and bit sizes are not stated in the materialInformation required |
| Model | Configuration | Key ranges | Availability |
|---|---|---|---|
| HDP-5 | Small range, plain variant | 0.015 to 0.500 N·m / 0.15 to 5.00 kgf·cm / 0.15 to 4.45 lbf·in | |
| HDP-50 | Large range, plain variant | 0.15 to 5.00 N·m / 1.5 to 50.0 kgf·cm / 1.5 to 45.0 lbf·in | |
| HDP-5S | Small range, S variant | 0.015 to 0.500 N·m / 0.15 to 5.00 kgf·cm / 0.15 to 4.45 lbf·in | Range identical to HDP-5; the difference between the variants is not stated in the material |
| HDP-50S | Large range, S variant | 0.15 to 5.00 N·m / 1.5 to 50.0 kgf·cm / 1.5 to 45.0 lbf·in | The size named in the source folder |
Certifications are only published once a certificate copy can be produced, so this section is deliberately empty rather than populated with assumed approvals. Tell us which approvals your application requires and we will confirm what is available for this instrument.
The following are required for a complete specification but are not stated in the documentation supplied to us. They are listed rather than estimated:
This one measures at the screw, not at the tool. The detector head is fitted with a bit, engaged in the screw head and turned by hand, so the reading includes the friction of the joint and the thread as well as the torque left by the driver. A tester that holds the tool measures the clutch setting, which is a different number and is taken before the screw goes in.
Both have uses and they are not interchangeable. Loosening torque is the higher of the two, because it has to overcome static friction, so it is the figure used when the question is whether a screw will stay put. Tightening torque can only be checked on a screw that has not yet been disturbed, which in practice means sampling on the line rather than at final inspection.
The screw size and head type, the torque the driver is set to, whether the check is on the line or after assembly, and whether readings have to be printed or sent to a computer. The bit that engages the screw head also has to be specified, since the detector head is supplied without a stated bit size.
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