How do single stations operate?
They have independent (unique) manufacturing operations but are coordinated within a larger production system.
Define a manually operated station
Worker controls the machine and handles the work.
Define a semi-automated operated station
A machine is controlled by a program, however a worker attends to the machine every cycle (i.e. loading/unloading material).
When can multiple machines be assigned to one worker?
When the worker’s active time is significantly less than the machine’s operating time.
Define a single station automated cell
A fully automated machine capable of unattended operation for longer than one machine cycle (i.e. worker periodically loads parts or tends to the machine)
Three benefits of single station automated cells
- Reduced labour costs
- Higher production rates
- Easiest and least expensive form of automation (multi-station systems can be built and debugged incrementally)
How does unattended production handle part storage?
The station holds both raw work parts and completed work units. This may require two storage units (one for raw parts, one for completed parts).
What are automatic transfer systems in the context of unattended production?
Automated systems transporting parts between a storage unit and machine (unloads finished parts, loads raw parts).
What does unattended production entail?
A machine which performs every step of processing/assembly automatically
How might a worker interact with an unattended production system?
Worker resupplies raw parts, removes finished parts, changes worn-out tools, and tends the machine as needed.
What are some safeguards to consider when building an unattended production system?
Recovery and error detection systems.
This stops the machine from creating unsafe working conditions, self-destructive operations, or damage to work units.
How would a work identification system work in an automated environment?
It distinguishes between different work units to apply the correct processing sequence. Only required when an automated system manufactures multiple work units.
What is a work identification system?
A system which identifies a part/product style, and runs pre-prepared programs specific to that product style. (i.e. installation of heated seats vs standard seats in a vehicle)
What does an automated cell need in order to operate unattended for extended periods?
It requires the ability to automatically transfer of parts between storage and the processing station
Why is the unattended time of an automated cell usually less than its theoretical maximum?
Because the worker needs time to unload the finished pieces and load new work units
How can the capacity of a storage system impact scheduled tool changes?
Creating a time interval equal to the tool change cycle allows tooling to be changed during scheduled machine downtime.
What does designing storage for a full shift enable?
Prevents unnecessary downtime
What is “lights-out operation” in manufacturing?
Machines run unattended during night or middle shifts.
What is the minimum capacity of a part-storage system in an automated cell?
1 (lol no shit?)
A two-position Automatic Pallet Changer
(APC) swaps pallet fixtures between the machine work area and load/unload area. What is this an example of?
A system with one-part storage capacity.
See module 5, pg 13, fig 14.2
What are the two positions involved in a two-position APC?
The machine worktable and the manually operated load/unload position
A system has a one-part storage capacity. The worker is expected to…
Unload finished parts and load new ones.
What is the difference between one-part storage capacity and zero storage capacity?
Zero storage - Machine waits for worker to load/unload parts
One-part storage - Machine works on part as the worker loads the next part
What is the benefit of having a part-storage system with a capacity greater than one?
This means the machine can be left unattended for longer periods of time.
See module 5, pg 13, fig 14.3
