Digital Micrometer for Paper and Board

What is the Digital Micrometer for Paper and Board?

A digital micrometer measures the thickness of a single sheet, a stack or a laboratory hand sheet with a flat spindle under a defined low pressure. It is a simple bench instrument for rapid checking and for stack-based bulk calculation.

Overview

The instrument is a micrometer with a flat measuring spindle and anvil, a friction or ratchet drive that limits the applied force, and a digital display reading to 1 µm. Because it measures a single sheet or a stack, results can be used to calculate the average sheet thickness in a stack, although the pressure and contact area differ from those of the standard paper caliper method, so the value is not automatically comparable. Measuring a stack with many sheets improves repeatability by averaging formation differences, while measuring individual sheets reveals thickness variation. The spindle must be clean and free of burrs, the zero setting should be checked with the spindle closed, and the friction drive must be set to the specified measuring force.

How does it work?

Because paper is compressible, thickness depends strongly on the pressure applied, the area of the measuring foot and the dwell time. Standards therefore define the contact pressure, usually 100 kPa for paper, the foot diameter, and the time between lowering the foot and reading the value, so results from different laboratories are comparable. A dead-weight instrument applies the load through calibrated masses on a fixed-area foot and reads displacement with a dial gauge or digital sensor, while motorised instruments lower the foot at a controlled speed and hold the specified pressure for a set interval. Board and tissue thickness use larger pressures or different foot geometries, and corrugated board requires a foot large enough to bridge the flutes and a comparator plate, so the correct geometry is defined by the product standard rather than chosen freely by the laboratory.

What are the key features?

• Flat spindle and anvil measuring faces
• Friction or ratchet drive limiting measuring force
• Digital display with 1 µm resolution
• Zero setting check with spindle closed
• Stack measurement and bulk calculation
• Data output or hold function

What are the technical specifications?

A typical digital micrometer for paper and board configuration offers reading resolution of 1 µm, measuring range of 0–12.7 mm or 0–25 mm, measuring force of 5–10 N with friction drive, spindle diameter of 6.35 mm or 16 mm options, sheets per stack reading of 10–50 for bulk calculation and accuracy of ±2 µm over the range. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Digital Micrometer for Paper and Board is used in rapid single-sheet thickness checking, stack thickness for bulk calculation, laboratory hand sheet characterisation and field checks on board and packaging stock. Across the wider Thickness Testing class, laboratories also deploy it for thickness and apparent density of paper and board, corrugated board caliper verification and tissue and lightweight paper thickness testing.

Which standards and certifications apply?

Relevant standards and methods include ISO 534, ISO 3034, ISO 12625-3, TAPPI T411, TAPPI T551, ASTM D645 and IEC 61010-1. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Condition specimens to the standard atmosphere before testing, because thickness changes with moisture and the change is not fully reversible within a short time. Clean the foot and anvil, since dust or fibre on the surfaces is added to the reading, and check the foot diameter and parallelism at intervals. Lower the foot gently at the defined speed, take the reading at the specified time and lift the foot between readings, and avoid taking measurements on the same spot twice. Verify the instrument with certified shims or gauge blocks at several points in the measuring range, and keep the calibration certificate with the instrument record.

How do I select the right Digital Micrometer for Paper and Board?

Choose a digital micrometer for quick checking and for stack-based bulk calculations, but use a standard caliper where the method specifies 100 kPa contact pressure. Confirm the measuring force and spindle diameter, and keep gauge blocks available for zero and range verification, since a micrometer that is not checked silently misreports thickness.

How does it compare with other Thickness Testing variants?

Select the instrument from the product standard you test against. Flat paper and board are measured with a 100 kPa dead-weight or motorised instrument with a defined foot area, tissue papers require the smaller pressure and foot of their own method, and corrugated or heavy board needs a dedicated gauge with the correct foot diameter and a rigid comparator plate. Choose a motorised instrument when many readings are needed or when operator technique must be removed, and a dead-weight instrument when simplicity and direct traceability of the applied load matter. An online caliper is specified only when continuous reel or sheet thickness data must be recorded during production, since it is measured without contact pressure and therefore correlates with, rather than reproduces, laboratory values.