Car body assembly: introduction to welding shop glue
The body structure is strengthened Metal bonding adhesive choices across the car body follow the substrate and cure schedule of each joint zone.
Vehicle body structural adhesive is mainly a thermosetting structural adhesive with modified
epoxy resin as the matrix. Its main function is to combine with riveting, spot welding and other rigid connections:
l Improve the strength of the body, high modulus, high Tg;
l Reduce cost, reduce solder joints;
l To achieve the combination of different materials, and play the role of sealing and shock absorption;
l The length of the body structure glue varies from 30m to 200m, and the corresponding weight of the structure glue is 0.2kg ~1.5kg;
l Structural adhesive is suitable for structural bonding of metal parts with a gap less than 1mm;
Introduction to welding shop glue
Rapier glue
Edge glue is a thermosetting one-component modified epoxy glue:
l Corrosion resistance, no solvent, PVC, isocyanate;
l Compared with welding, there is no stress concentration
phenomenon, and the impact resistance and aesthetic effect are good;
l Suitable for high strength bonding between different metals;
l Good adhesion on oily surface, <2g/g/m2;
l The particle size of glass microspheres added in the adhesive is 0.15mm~0.25mm, and the designed gap is 0.15~0.2mm;
l The bicycle weight is over 200g.
• Full package structure: D surface must ensure that the glue coating
surface>0mm
• Half package structure:
there is glue overflow at the edge of the bend
• Open edge structure:
there is overflow glue on C side, and no 100% filling requirement
• Water drop edge structure: D surface must ensure
that the glue coating surface>0mm
Car Body Assembly: Introduction to Welding Shop Glue
| performance index | JOME1750 | JOME 2022 |
| Application site | Metal + metal | Metals + composites |
| chemical composition | Single component epoxy | Two-component epoxy |
| pigment | White/blue/purple/other | White/black |
| Resist flow | 23℃ 10mins, ≤ 3mm；170℃ 20mins, ≤ 3mm | – |
| density g/ml | 1.38 | 1.15 |
| mixing ratio | – | 100:50 |
| Hardness Shore | – | 82D |
| dynamic viscosity | 300Pa.s | 20000±5000mPa.s |
| curing temperature | 20mins/170℃ | RT 24h/ 80℃1h/ 40℃ 16h |
| Shear strength (Fe-Fe) | 38MPa | 35MPa |
| T- peel strength | 8.31N/mm | 7.5 N/mm |
| tensile strength | 38MPa | – |
| Extensional elongation | 6% | – |
| Glass transition temperature Tg | 108℃ | 70℃ |
| applicable temperature | -40~150℃ | -50~150℃ |
Introduction to coating workshop glue
Body sealant
In car body assembly, welding seam sealant is an important type of glue used in body painting. It is applied to the
external welding seam before body surface paint, and becomes an elastic body with certain
bonding strength after curing. It can effectively play a role in sealing leakage, enhancing the rust prevention ability of the body and increasing the aesthetic performance of the body.
PVC The process of applying glue is: metal trimming, rough sealing, primer, fine sealing and drying
a) Coarse sealing: the body, wheel cover and engine room welds are sealed and brushed smooth according to the process requirements.
b) Small sealing: sealing of the water tank, four doors, engine cover and trunk shall be applied with sealing glue according to the process requirements.
c) Anti-rock hitting coating: Anti-rock hitting coating inside the wheel cover and under the body is sprayed according to the process requirements.
| JOM-1300 | performance requirement |
| surface | Black / grey |
| density | 1.2-1.4g/ml |
| Construction temperature | 20~35℃ |
| drying temperature | RT/40℃ |
| spraying thickness | 0.5~3mm |
| Solid content | ≥70% |
| dynamic viscosity | ≥ 10Pa.s |
| Fluidity | 30mins ≤ 2 mm 25℃ |
| adhesion | > 90% CF |
| Resistant to impact | 25 Kg.cm |
| Bendability: 20mm inner diameter | No cracks, no spalling |
Introduction to the glue used in the final assembly workshop
Body exterior/glass bonding
| performance index | JOMP 1658 | JOMS 3360 | JOMS 2018 | JOM 9130 |
| chemical composition | One-component polyurethane | Monocomponent modified polyether | Two-componenthybridization | Two-component acrylic |
| pigment | black | Black / white | A black / B white | A white / B gray |
| density g/ml | 1.25g/ml | 1.5g/ml | 1.08g/ml | 1.0g/ml |
| dynamic viscosity | Extrusion rate 40~60g/min | A100/ B30 Pa.s | A100/ B30 Pa.s | |
| Table dry time 25℃ | 10~40mins | 10~20mins | – | – |
| mixing ratio | – | – | Volume ratio 100:50The mass ratio is 100:55 | 10： 1 |
| Operation time 25℃ | 5~20mins | 5~10mins | 25mins | 5mins |
| Shore A hardness | 55~65 | 60 | 78 | – |
| Curing rate 25℃ | 3~4mm RT 24h | ≥ 2.8mm RT 24h | 7d/ 60℃ 4h | Initial fix 17minsThe final solid RT lasts for 24 h |
| shear strength | 4.5MPa | ≥ 2MPa | 7.2 MPa | 17 MPa |
| tensile strength | 8MPa | ≥ 2.2MPa | 7.6 MPa | 23MPa |
| Extensional elongation | ≥400% | ≥250% | 300% | 50% |
| working temperature | -40~ +90℃ | -40~ +110℃/150℃ 1H | -50~120℃ | -40~ +80℃ |
Assign each body joint a function and a process history
In car body assembly, the first selection question is what the joint must do before and after curing. A structural overlap, a folded panel edge and a seam exposed to water are different engineering problems. Mark the load path, the sealing path and the visible finish on the drawing before selecting the adhesive family. Where bonding is combined with welding or riveting, the adhesive should be evaluated as part of that joining method. Mechanical attachment can influence local contact, heat exposure and the way the joint carries load; it does not remove the need for a sound adhesive interface. The actual sheet surface also matters. Bare laboratory metal may not represent material carrying a production coating, approved lubricant or pretreatment residue. Use specimens from the intended surface route and record their condition before dispensing. Product guidance on bonding a particular surface is more useful than a broad claim that an adhesive bonds metal. Next, follow the part through the manufacturing sequence. Ask when the joint closes, how it is held, what washing or painting steps follow, and where the adhesive receives its curing conditions. Oven air conditions do not necessarily describe the thermal history inside every bond line. Panel thickness, shielding and surrounding assemblies can affect how a joint heats. Why choose a material from a strength table if its required cure cannot be delivered at the joint? It’s more practical to review the complete process history before comparing final mechanical properties. The structural adhesives for industrial assembly category offers a starting point for material discussions, with the substrate finish and joining route specified. Review whether the joint must resist sliding, opening at an edge or sustained deformation under load. Those loading modes can expose different weaknesses. A formulation that performs well in a simple overlap test may need additional evaluation in a folded edge or a mixed-material panel. Keep the distinction between temporary handling stability and final cured performance explicit, especially when parts move to another workstation before cure is complete.
Inspect bead continuity and the failure surface after conditioning
Process validation for car body assembly should connect dispensing observations with the finished joint. Check whether the bead follows the intended path, including starts, stops, corners and changes in flange width. Closing the panels can spread the bead, but apparent squeeze-out at an edge does not prove that the entire hidden overlap has filled correctly. Use representative sectioned joints or another suitable inspection method to confirm coverage, contact and gap control. Examine whether local panel movement displaces adhesive from an area that should remain bonded. Where a seal is intended, trace the complete water path instead of inspecting only the most accessible seam. Adjacent holes, fastener locations and transitions between materials can bypass an otherwise continuous bead. Compare the adhesive sealants for joint sealing with that geometry and the expected movement in mind. Paint appearance and sealing behavior should be checked after the actual coating sequence, including exposure to the intended cleaning materials. Do not assume that an acceptable uncured surface will remain acceptable after later processing. Mechanical evaluation should include the load modes identified in the joint design. Inspect both sides after failure and distinguish adhesive separation, failure within the adhesive and failure within a coating or substrate. If a coating detaches from the metal, replacing the adhesive may not address the weak layer. Condition representative joints for moisture and temperature changes that match the intended service, then examine the edges and the contact between dissimilar materials. Differential movement may load those interfaces even where the original assembly looked uniform. A water leak, loss of adhesion and cosmetic distortion should be recorded separately because their causes can differ. When production changes, revisit the relevant part of the qualification: a new sheet coating affects the interface, a revised fixture affects contact, and a changed thermal route affects cure. Keep the material identity, surface preparation, dispensing method and failure observations together in the trial record. That makes it possible to distinguish a material limitation from a change in how the body joint was produced.
JOME manufactures the full JOME product catalogue in its own factory for customers in more than 30 countries. Readers continuing from Introduction to Different Adhesive Schemes for Various will find the JOME adhesive factory in Shanghai covers the full portfolio, and project questions go to the reach the JOME technical staff.