Mix an NR-45 compound batch and calender lining sheet

What is going on

Bassline Irrigation Systems needs 120 kilograms of NR-45 natural rubber compound mixed and calendered into 3 millimetre lining sheet. The open mill was tagged out last week when its trip cable was found slack and it has now been adjusted and retested, but the tag must be checked before use. A recent SBR batch was dropped above its dump temperature and accepted only with concession, so the technical team is watching mixer temperatures. Curatives must be weighed and held apart, extraction must be running and the rheometer must confirm the batch before it is released to stock and calendered.

Your brief

Weigh, mix, finish, test and release a batch of NR-45 to the Rubber Compound Mixing Procedure with full lot traceability, confirm the mill is safe to use, then calender the compound into 3 millimetre sheet with thickness checks recorded, and update the stock and job card records.

Work through it

You do not need to do it all. Doing a few of these will show you what the work is like. Your ticks and notes stay on this device.

• Read the Rubber Compound Mixing Procedure and the mills and calenders section of the Machine Safety and Isolation Policy and list the checks required before the mixer and mill are used.
• Check the WHS register entry for the mill trip cable and confirm from the tag and the start of shift trip test that the mill is released for use, recording the test result.
• Weigh every ingredient on the NR-45 recipe supplied to the stated tolerance, record actual weights and lot numbers from Raw Materials and Compounds Stock on the batch card, and keep the curatives separate.
• Describe the internal mixer charge sequence, ram and rotor settings, the dump temperature and what you do if the batch temperature approaches the maximum, with reference to the SBR concession in the nonconformance register.
• Describe finishing on the open mill, including the nip setting, curative addition temperature, the cutting and folding technique and where your hands must never be.
• Run the rheometer on a batch sample and compare cure time, scorch time and torque with the recipe limits; record the result and the release decision, and describe what happens if a value is outside limits.
• Release the batch in Raw Materials and Compounds Stock with its batch number, return curatives and chemicals to their stores and update the Hazardous Chemicals Register quantities.
• Calender the compound into 3 millimetre sheet, record thickness at five points across the web at the frequency on the sheet, and complete the job card for JC-26-3324.

What someone in this role would produce

• Pre-use checks and mill trip test record
• Completed batch card with weights and lot numbers
• Rheometer result and release decision
• Stock release and chemical register update
• Calender thickness records and completed job card