The world of injection molding is constantly evolving. With new processes and new process control equipment, advanced and more complicated tooling, newer sophisticated Molding machines, and new materials development. With that said, there is one thing that does not change and that’s time. Molding machine efficiency is critical in today’s very demanding schedules, multiple colored products, part sequencing, TPS, JIT, Lean Manufacturing (which ever decade you prefer).
Process Optimization should be on everyone’s mind in your technical department. It should be their way of life.
These are 11 steps I followed religiously as a processor which helped me constantly optimize our process.
- Adjust Heats
Barrel heats should be set to reflect a melt temperature that is in the center of the process temperature range recommended by your material supplier.
- Nozzle Tip
Your nozzle tip must the correct dimension, orifice and radius. If you aren't certain, double-check and make sure yours is.
- Regular Maintenance
Tooling must be PM’d by your tooling maintenance. Make sure it is cleaned, greased and venting properly.
- Minimize Clamp Open Distance
This allows for part drop or robotic part removal. Break away velocity and position. Open slow down velocity and position. Clamp close velocity and slow down position. This should be based on ejector pin or leader pins, horn pin, and guide length. Velocities should be set for a smooth but quick open and close.
- Fill Time
Once rheology of the material you are processing is understood, fill the cavity as fast as possible based off the rheology curve.
- Establish Fill Only Weight
Fill only weight will need to be established. This is basically your first stage fill. I would prefer to say fill volume instead of fill weight. The part should be approx. 95% full by volume after first stage, give or take 3 to 4 %, depending on part design. This depends on a Decoupled 2 or process.
- Second Stage or Your Pack Stage
This can be pack or hold depending on process established. Pack pressure should be set to fill and pack part to complete packing of part. Under packed or over packed parts can result in dimensional issues and aesthetics (i.e.flash or sinks).
- Hold Time
Hold time should be established off of part weight, appearance and dimensions. Gate seal is not necessarily a requirement for all parts.
- Cure Time
Cure time is based off HDT (heat deflection temperature). This is based off your water temperature and cooling time.
- Part Ejection
Part Ejection depends on the part and runner configuration as well as part removal preference. Ejecting on the fly maybe possible if you are dropping onto a conveyor belt or into a chute. Sometimes part configuration will dictate a two-stage ejection if deep pockets or ribs are present.
- Adjust Robotic Part Removal Settings (if applicable)
If robotic part removal is required then minimize part removal time by speeds, position and delay times.
This will increase your efficiency and reduce your machine capacity, which will allow for more business, without additional molding machines.
If you would like more information about setting up a sound purge process, or would like for me to take a look at your color change or material change procedure and cost, please comment below or email firstname.lastname@example.org.
Ready to reduce your production downtime to protect your profits? Learn more about how purging compounds and process efficiency work in tandem.