What should be paid attention to when processing rubber dust cover?

The processing of rubber dust cover should focus on the four core requirements of structural integrity, elasticity and toughness, reliability of dust-proof seal and weatherability and durability, and adapt to its dust-proof, waterproof and impurity-proof functions on machinery, automobiles, household appliances and other equipment. The specific precautions are as follows:

Selection and pretreatment of raw materials

Accurate matching of materials: Choose rubber materials according to working conditions, such as chloroprene rubber (CR) or styrene-butadiene rubber (SBR) for dust cover of automobile chassis, taking into account weather resistance, wear resistance and tear resistance; Silicone rubber (VMQ) can be selected for the dust cover at the motor shaft end, which is suitable for high and low temperature (-60℃~200℃) environment; The dust cover of hydraulic equipment is preferably made of fluororubber (FKM), which is resistant to hydraulic oil corrosion.

Optimize the formula to improve the flexibility: add plasticizer and softener to adjust the rubber hardness (Shore hardness should be 40 ~ 60) to ensure the tensile resilience of the dust cover (elongation at break ≥300%) and avoid tensile cracking during installation; Add anti-ozone agent and anti-ultraviolet agent to improve the aging life of outdoor use.

Pretreatment of raw materials: raw rubber needs to be mixed in advance to ensure uniform mixing and no particle impurities; The dust cover containing metal inserts should be degreased and phosphatized to improve the bonding strength with rubber and prevent degumming in use.

Key points of mold design and processing

Cavity design is suitable for telescopic structure: rubber dust covers are mostly corrugated telescopic structure, and the mold needs to accurately design the number of corrugations, the size of peaks and valleys, and make arc chamfering (R≥0.5mm) at the transition of corrugations to avoid cracking caused by stress concentration after molding; The tolerance of the mold cavity is controlled within ±0.03~±0.05mm, so as to ensure the accurate matching between the inner and outer diameters of the dust cover and the installation position of the equipment.

Exhaust and demoulding design: the mold should be provided with an even exhaust groove (0.01~0.02mm in depth) to exhaust the gas generated in the vulcanization process to prevent bubbles and material shortage on the surface of the dust cover; The demoulding inclination is set to 1 ~ 2, and the ripple position can be increased to 3 to avoid pulling the rubber surface or causing ripple deformation during demoulding.

Accurate positioning of the insert: For the dust cover with mounting flange or metal skeleton, locating pins and pressing mechanisms should be set in the mold to ensure that the coaxial deviation between the insert and the rubber layer is ≤±0.05mm, so as to prevent the offset of the insert from affecting the assembly and sealing effect.

Strict control of molding process parameters

Control of core parameters of vulcanization process: adopt flat vulcanizer or injection vulcanizer for molding, and strictly follow the three elements of "temperature-pressure-time":

Temperature: Adjust according to the material (for example, the curing temperature of CR is 150~160℃ and the curing temperature of FKM is 180~190℃), and the deviation is ≤ 2℃, so as to avoid the lack of elasticity caused by insufficient sulfur or the increase of brittleness caused by excessive sulfur;

Pressure: controlled at 8~15MPa to ensure that the rubber fully fills the mold cavity and the corrugated molding is full;

Time: calculated according to the thickness of dust cover (generally, the thickness of 1mm corresponds to the vulcanization time of 1~1.5min) to ensure complete vulcanization.

Avoid stretching deformation: the dust cover after vulcanization and demoulding needs to be naturally cooled to room temperature, and stretching and extrusion at high temperature are strictly prohibited; Corrugated dust covers should be laid flat to avoid corrugated collapse and deformation caused by stacking.

Secondary machining accuracy control: if it is necessary to cut the installation edge and punch holes, it is necessary to use numerical control cutting equipment to ensure that the incision is smooth and burr-free; Special rubber adhesive shall be selected for the bonded dust cover, and the bonding surface shall be rough and clean to ensure the bonding strength ≥ 5N/cm.

Quality inspection and performance verification

Size and appearance detection: use calipers and image measuring instruments to detect the inner and outer diameters, ripple size and mounting edge thickness, and the tolerance shall meet the requirements of the drawings; Appearance should be free of bubbles, lack of materials, cracks and flash, and the ripples should be even and full.

The performance test fits the actual working conditions:

Stretch rebound test: stretch to rated elongation (generally 100%~150%) and then rebound, repeated for 1000 times without cracking and permanent deformation ≤ 5%;

Dust-proof and waterproof test: installed on simulation equipment, tested by dust spraying and high-pressure water spraying, no impurities enter and no water seepage phenomenon;

Weathering and aging test: after high and low temperature cycling (-40℃~120℃) and ozone aging test, the hardness changes ≤ 5 Shore, and there is no crack or stickiness.

Batch consistency control: take 5% samples from each batch for full performance testing, and record vulcanization parameters and size data to ensure stable performance between batches.

Packaging and storage protection requirements

Anti-deformation packaging: corrugated dust cover is packaged separately with customized blister box or paper holder to avoid extrusion deformation; A single product is covered with PE bag to prevent the surface from being contaminated with oil and dust.

Storage environment control: Store in a cool and dry warehouse (temperature 10~25℃, humidity 40%~60%), away from heat sources, ultraviolet rays and organic solvents, and conduct regular sampling inspection during the warranty period to prevent rubber from aging in advance.