Material Analysis
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Large performance differences between different batches of general-purpose polyethylene raw materials
Problem Phenomenon
After changing the raw material batch, the product shows dimensional deviations, appearance changes, or performance fluctuations.
Different batches of raw materials differ in melt flow rate, density, molecular weight distribution, etc., resulting in the need to readjust the process parameters.
Cause Analysis
（1）The melt flow rate (MFR) of different batches of raw materials fluctuates
（2）The molecular weight distribution and crystallinity of different batches of raw materials differ
（3）The raw material supplier is changed or the production process is adjusted
（4）The storage conditions and time of the raw materials are different, and the performance changes
（5）The content of additives (such as antioxidants, lubricants) differs
Solution
（1）After each batch of raw material arrives, test key indicators such as MFR and density, and compare with standard values
（2）Establish a batch management system, use different batches of raw materials separately, and mix batches when necessary
（3）Adjust the process parameters when changing batches, and conduct trial mold verification first before production
（4）Communicate with the supplier and require control of the performance fluctuation range between batches
（5）Use raw materials on a first-in, first-out basis to avoid excessive storage time
Key Takeaway
Batch differences are caused by fluctuations in raw material production, and a sound incoming inspection and batch management system needs to be established.
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