- Model
- TH100 / TH110 / TH120 / TH140
- Hardness scales
- HL, HB, HRC, HRB, HRA, HV and HS, converted on the instrument
- Measuring range
- 170 to 960 HLD, 17.9 to 69.5 HRC, 19 to 683 HB, 80 to 1042 HV, 30.6 to 102.6 HS
- Impact device
- D type supplied as standard; DC, DL, D+15, C, G and E types available to order
- Measuring direction
- 360°, including vertically down, upward and at an angle
- Built-in materials
- Steel and cast steel, alloy tool steel, stainless steel, grey and nodular cast iron, cast aluminium alloy, brass, bronze, pure copper and forged steel
- Display
- 128 × 64 dot matrix LCD on the standard model; colour screen on one variant
- Interface
- USB for data transfer, with transfer to a micro printer on the variants that carry one
- Storage
- 600 measurement groups on the standard model, as low as 100 and as high as 600 according to variant
- Supply
- Two AA cells on the standard model, giving about 100 hours of operation; rechargeable cells on the printing and metal-housing variants
A Leeb hardness tester is bought for a problem that a bench machine cannot solve: the part is already on the machine, in the structure or on site, and it cannot be brought to a hardness tester. The method answers that by striking a small impact body against the surface and reading how far it rebounds, which takes a second, needs no preparation beyond a clean area, and leaves a mark measured in tens of micrometres.
What it costs is a measurement whose validity depends on the part rather than on the instrument, and that is the theme of everything below.
What the instrument is
An impact device and a hand-held body. The impact device holds a spring-loaded impact body with a hard spherical tip; when it is released against the surface, the tip strikes and the body rebounds, and a sensing coil in the device times both the impact and the rebound. The body of the instrument supplies the electronics, the display, the keypad, the storage and the interface, and it is the part that changes across this range.
The impact device is interchangeable, and that is what makes one instrument cover a very wide range of work. The D type supplied as standard is the general-purpose device for normal surfaces. The others are bought for geometry or material the D type cannot deal with, and each carries its own specimen requirements and its own conversion tables.
The scales and what they mean
The measurement is a Leeb value, written HLD for the D device, and the instrument converts it to Brinell, Vickers, Rockwell and Shore scales so that the figure on the drawing can be shown directly. Seven scales are available from one reading, and the conversion is arithmetic performed inside the instrument rather than a measurement of the other scale.
That distinction matters when a specification is tight. A converted value carries the uncertainty of the conversion on top of the uncertainty of the measurement, so a converted figure is a good incoming-inspection and screening tool and a poorer basis for arbitration than a direct bench measurement. The ranges the material gives are broad - 170 to 960 HLD, 19 to 683 HB, 80 to 1042 HV - and each material group has its own narrower band, which is what actually applies when a specific part is measured.
Reading a valid number
Three conditions decide whether a Leeb reading means anything.
The first is the mass and rigidity of the part. The impact sends a small amount of energy into the part, and if the part is light or poorly supported, that energy moves the part instead of returning to the rebound. The material gives a minimum specimen weight for each device in three tiers, from directly measurable, through needing support, to needing firm coupling, together with a minimum thickness for each. Those figures are the practical guard, and they are checked against the part before the instrument is chosen.
The second is the surface. Each device carries a mean roughness requirement, from Ra 0.4 µm for the C device up to Ra 6.3 µm for the G device, and a surface rougher than that gives a reading of the surface as much as of the material. The measurement point is normally cleaned and, on a rough part, ground or filed flat.
The third is orientation and the correction that follows from it. The range is described as 360°, which means the device can be used in any direction, but a reading taken vertically upward and one taken vertically downward do not start from the same energy state, and the instrument applies a direction setting. Selecting the direction correctly is part of taking the measurement, not an optional refinement.
Choosing within the range
The range spans a pen-type instrument at one end and dual-display metal-housing instruments with an integral printer at the other, and the choice between them is about where the record is produced rather than about the measurement.
The pen type is the one for a surface the larger body cannot reach, and it holds the least data. The standard model is the general-purpose instrument with the largest storage and the simplest interface. The colour-screen variant displays all seven scales together and prints over Bluetooth. The variants with an integral thermal printer produce a complete measurement report at the point of measurement, listing the model, the serial number, the date and time, the sensor type, the material, the impact direction, each individual reading, the average and the extremes - which is the form taken when a batch record has to be signed where the work is done rather than in an office.
Measurement limitations and selection considerations
The material flags two inconsistencies in its own specification and both are carried here rather than resolved.
The accuracy differs inside the same model designation: the standard model is stated as HRC ±1.0 and HLD ±6.0, while the colour-screen, printing, metal-housing and dual-display variants are stated as HRC ±0.8 and HLD ±6.0. Storage capacity varies from 100 to 600 groups across the range. The interface is described as USB in the specification while the accessory list names an RS232 cable, and the calibration block is listed as standard while the material also notes that some variants ship without one.
None of these is a defect; they are the normal consequence of a range described in promotional material rather than in a datasheet, and they are listed so that a quotation can pin them down instead of assuming.
The limitation that belongs to the method rather than to this range is worth repeating. A converted hardness figure is not a bench measurement, and where a specification names a bench method or a governing standard of its own, the portable reading is a screening value rather than the record. That is a question about the specification, and it is answered before the instrument is chosen.
Ordering
The items that fix the answer are the material and its grade; the smallest and thinnest part to be measured, with an indication of whether it can be supported; whether the part can be brought to a bench at all; the surface condition that can be achieved at the measuring point; the hardness scale the specification names; whether a printed or exported record is required and where it has to be produced; whether more than one impact device is needed, and which geometry or material each is for; and the quantity of parts to be inspected per shift. Stating the variant explicitly is necessary, because the designation TH110 covers five configurations in this range. Quantity, destination port and required delivery date complete the enquiry.
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.
