Heat-sealing jaw

01

Match the jaw to the material's sealing window

Merabtene and co-authors (BioResources, 2022) set sealing parameters on a laboratory heat sealer and ran them on an industrial VFFS machine. PE-coated paper first sealed at 90 °C and handled up to 220 °C (70 g/m² paper with 15 g/m² PE) or 190 °C (90 g/m² paper with 30 g/m² PE) before browning, while an OPP/PE plastic reference started sealing at 100 °C and shrank around the jaws above 140 °C. [1]

The study found the minimum dwell for the paper material was 0.4 s at 100 °C, used a 2 s dwell when mapping sealing temperatures, and reported that the process parameters found on the laboratory sealer transferred directly to the production machine. [1]

US patent 6,663,977 on a low-temperature heat-sealable polyester film reports heat seals made to ASTM F88 with a 40 psi sealing bar pressure, a 0.25 in (0.64 cm) wide bar and a 1.0 s dwell with heat on the upper bar only, and other tests at 0.5 s dwell, 40 psi and a 1 in wide bar; it notes that sealing pressures may range up to about 90 psi of sealing bar. [3]

Editorial calculation: 40 psi is about 2.8 bar (40 × 0.0689), within the 3.1–6.5 bar range of jaw surface pressures in the VFFS study, so laboratory seal tests and machine jaws can be set to comparable pressures. [3] [1]

It cites earlier studies on polyethylene films that found sealing temperature and dwell time strongly affected seal strength while sealing pressure had little effect, and it measured seal strength by 180° T-peel to ASTM F88 on 25 mm strips. [1]

Editorial note: ask the film supplier for the sealing window and the jaw supplier for the temperature range and uniformity across the jaw face; set dwell from line speed and confirm with peel tests on your material.

Give the supplier the machine type and model, jaw position (horizontal, longitudinal), jaw length and seal width, profile (flat, serrated, pattern), material and thickness, sealing temperature range, dwell and cycle rate, available force or surface pressure, heater power and voltage, sensor type, coating, integrated knife, and quantities.

02

Choose profile, width and surface pressure

The study's horizontal jaws were 11 mm wide in flat and serrated profiles, each applying 2,356 N; the paper's Table 2 gives a contact area of 6,160 mm² and 3.8 bar for the flat tool and 7,616 mm² and 3.1 bar for the serrated tool, with 6.5 bar on the longitudinal sealer and 4.2 bar on the laboratory bar. [1]

The serrated profile gave slightly lower seal and compression strength than the flat profile on the paper material because of localised shear that damaged the surface; the plastic reference had about three times the seal strength of the paper with the serrated jaw and about twice with the flat jaw. On the paper material, seal strength barely changed with pressure once about 3 bar was applied. [1]

US patent 11,260,603 explains that form-fill-seal jaws are knurled with a saw-tooth or square-wave pattern so that the films stretch, which increases seal area and mechanically interlocks the front and back films; it lists jaw pressure, dwell time and seal temperature as the main variables, with seal temperature set by the packaging material and pressure and dwell adjusted by the operator. Its jaws use asymmetric teeth, with one tooth face at about 25–60° and the other at about 15–35° to the valley centre line, so that each peak enters the opposing valley off-centre to strengthen the seal at the package's inside leading edge. [2]

Editorial calculation: surface pressure equals jaw force divided by contact area, so 2,356 N over 6,160 mm² is 0.38 N/mm², or 3.8 bar; a jaw that applies the same force over a longer seal needs more force to keep the same pressure, so ask for the force at your jaw length. [1]

03

Specify the ridge radii on jaws for laminated carton material

Tetra Laval's US patent 8,572,936 addresses a jaw face for laminated carton stock (a paper or mineral-filled polypropylene base with polyethylene heat-seal layers, plus an aluminium foil or EVOH barrier layer for aseptic packs). It states the need to prevent polyethylene blisters or lumps at the seal, which impair sealing quality and can pierce the barrier layer. Its jaw face carries elongated projections separated by half-cylindrical cavities running along the seal, and the patent notes that the counter-jaw may carry a heated bar or induction heating instead of its ultrasonic sonotrode. [4]

Editorial calculation: at the 1.8 mm pitch, an 11 mm wide seal like the horizontal jaws in the BioResources study would cross about six ridges (11 / 1.8 ≈ 6.1); the patent's own jaw has three cavities between four projections on each side of the cutting plane. The radii are fractions of a millimetre, so ask the jaw maker how it machines and inspects them and how wear is checked. [4] [1]

Compare this rounded-ridge profile with the asymmetric saw-tooth knurl of US 11,260,603 above: one rounds the ridges to avoid lumps in laminated carton material, the other angles the teeth so each peak enters the opposing valley off-centre. Ask the supplier which profile it recommends for your material structure, and for a sectioned seal from a trial run. [4] [2]

04

Find heat-sealing jaw manufacturers

No manufacturer record has been reviewed for this product yet. Send your specification and CNFX will match it against manufacturer records.

05

Trace the jaw components

This is a functional reference built from the sources cited; it is not one maker's design.

06

Fill the specification fields with values for your machine

A heat-sealing jaw quotation needs values for your machine and material. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the machine, material and seal data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Machine: [type; model; jaw position]
Material: [structure; thickness; sealing window]
Jaw: [length; width; profile; knife]
Process: [temperature; dwell; cycles per minute; force]
Control: [heater; sensor; voltage]
Supply: [drawings; quantity]

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