Automated cell
- Consistent timing and force on every unit
- Checks and traceability built in
- Long build and debug time; changes to the part mean changes to the cell
Process guide
Automated Assembly Cells: From Molded Parts to Finished Units
A molded part is rarely the product. It gets a lid, a seal, an insert, a label, and a check before it ships. An automated cell does those steps in one place, the same way every time, if the parts were designed for it.
Inside a cell
What a typical cell does, in order
Each station is simple. The difficulty is making them work together at the planned rate.
An automated assembly cell feeds and joins molded parts. Snaps and bosses are covered in assembly features . Ultrasonic welding and heat staking are two joins a cell may use. Assembly on a molding program is a secondary operation .
An automated assembly cell feeds, orients, joins, and checks molded parts in one station. What it takes, how parts must be designed for it, and when not to.
Roles
Not sure which assembly question
The cell feeds and joins parts. Assembly features are the molded joins. Welding and heat staking are two ways the cell can close a joint.
| Page | Use it for |
|---|---|
| Automated assembly (this page) | Feed, orient, join, and check |
| Assembly features | Snaps, bosses, and datums |
| Ultrasonic welding | A fused joint the cell can run |
| Heat staking | A molded stud formed over another part |
| Secondary operations | Assembly scoped on the molding RFQ |
Inside a cell
What a typical cell does, in order
Each station is simple. The difficulty is making them work together at the planned rate.
- 1
Feed and orient
Bowl feeders, trays, or a robot picking straight from the molding press present each part the same way up.
- 2
Place and join
Parts are nested in fixtures and joined by pressing, snapping, screwing, welding, or staking.
- 3
Mark
Laser marking or labeling adds codes and dates so each unit can be traced.
- 4
Check and sort
Vision, force, and leak checks confirm each unit. Rejects leave the line before packing.
Design for automation
Parts a machine can handle without help
People can turn a part around and push it harder. A cell cannot, so the design has to do that work.
- Parts that are symmetric, or clearly not, so feeders find one right way up
- Lead ins and chamfers on every mating feature, so small position errors still go together
- Assembly from one direction, ideally straight down, instead of flipping partway
- Flat datum faces and gripping areas the fixture and gripper can find
- No flexible parts that tangle in a feeder, such as open springs or long thin legs
Checks
What a cell can check on every unit
Checking inside the cell costs little once it is built, and catches problems before they are packed.
| Check | What it catches |
|---|---|
| Vision | Missing parts, wrong orientation, short shots, and misprinted marks |
| Press force and distance | Inserts or pins that went in too easily or not far enough |
| Screw torque and angle | Stripped bosses and screws that did not seat |
| Leak or pressure decay | Seals, welds, and bonded joints that do not hold |
| Electrical test | Continuity through insert molded contacts and staked boards |
Choosing
Automated cell or manual assembly
Automation pays when volume is steady and the design is settled. Before that, people are usually faster to adapt.
Manual assembly with fixtures
- Starts quickly and follows design changes easily
- Handles flexible parts, cables, and awkward steps
- Quality depends on fixtures, work instructions, and checks
Keep reading
Related guides
The joining steps a cell runs, and the features that make parts easy to assemble.
Ultrasonic welding
A common joining station in assembly cells.
Ultrasonic weldingHeat staking
Fixing boards and brackets with molded posts.
Heat stakingInsert molding vs post assembly
Moving a step into the mold.
Insert molding vs post assemblyAssembly features
Molded features that guide parts together.
Assembly featuresSnap fit clips
Joints that need no tools.
Snap fit clipsSelf tapping screw bosses
Bosses that survive automated screwdriving.
Self tapping screw bossesAll processes
Every molding process and secondary operation.
All processesFAQ
Questions about automated assembly cells
Can a cell take parts straight from the molding press?
Yes. A robot can pick parts as the mold opens and pass them to assembly while they are still in a known position. That skips bulk handling, but it ties the cell to the press cycle.
When is it too early to automate?
While the part design is still changing, or while volume is uncertain. Each design change can mean new fixtures, grippers, and feeder tooling.
Do molded parts need tighter tolerances for automation?
Not always tighter, but more consistent. A cell can handle parts that are slightly off in the same way every time; it struggles with parts that vary from shot to shot or cavity to cavity.
What should be decided before designing a cell?
Target rate, the joining methods, which checks run on every unit, what happens to rejects, and how units are traced. Those set the size and cost of the cell.
Where are snaps and bosses covered?
In the assembly features guide. The assembly cell is what feeds and joins the parts.
Can assembly be quoted with the molding?
Yes. Assembly is scoped as a secondary operation on the molding RFQ. A full cell is a later choice when volume and checks are steady.
Next step
Get DFM feedback on your design
Assembly can be scoped with the molding RFQ. Upload CAD for an instant quote.