Extrusion Blow Molding (EBM): Operating Procedures

Extrusion blow molding is a processing technique used to manufacture plastic parts that are hollow. To run every plant, machinery and equipment there is an operating procedure for that plant and machine. In extrusion blow molding every industry follow its operating procedure but there are some common steps.

Common steps which are followed by every extrusion blow molders are

1. Pre-startup
2. Startup
3. Production
4. Shutdown

Pre-Startup

In pre-startup of extrusion blow molding first of all set-up sheet must be prepare. Collect and check for previous data for the plastic product you want to manufacture. Check for the plastic is it require drying? If drying is required then how much time and at what temperature? Answer of all these question must be there before starting up. Before starting up all the heaters, controllers, gauges, hydraulics and other thing are checked for their proper working. Faulty equipment is replaced before it disturb during actual production. Also check the resin for any contaminations.

Set-up sheet

Set-up sheet may be prepare for every material and every machine. Set-up sheet contains every detail of plastic and machine. Temperature profile and other material and machine setting parameters for that specific material and product.

Start-up

After pre-startup the next step is start up. Temperature of barrel and die is set, when required temperature is gained by all the heater then turn on the machine at low rpm and set the parison according to your product. When everything is according to your set parameters then speed up the machine. If machine was running with any other plastic than you want to process then purging is required. Purge all the material before running new material.

Production

Next to start-up is production. Production must be according to specifications provided to you. During production check dimensions, shape and other details of product also check for any spot or other problem in the final product. If problem is found it must be solved immediately. For example if you are producing a 30 litter jerry can you must check for neck details, weight, parting lines, black marks, and any other defects. Production rate depends on cycle time in extrusion blow molding. Increase in production may be due to faulty auxiliaries eg chiller.

Shutdown

Improper shutdown decreases the life of every machine. Extrusion machine must be always properly shutdown. The proper shutdown procedure is that a purging material is used to remove all the material in the extruder, die, and head. When purging material starts coming out then it is ready for shutdown.