News

Trade news

Company news

FAQ

Analysis of the Causes Behind Scorching and Poor Plasticization in Plastic Extruders

Time：

2018-08-30

During routine production, plastic extruders occasionally experience scorching and poor plasticization. Now, the editors at Shuangda Machinery will analyze the underlying causes for our customers. Plastic extruders are a type of plastic-processing machinery that typically feeds material into a cylindrical barrel and then uses a screw to extrude it. With the adoption of variable-frequency drive technology, pressure can be precisely controlled, allowing operators to select an appropriate linear speed. However, during operation, extruders sometimes suffer from inadequate plasticization—what’s the reason? 1. Scorching (1) High temperature readings or malfunctioning temperature-control instruments can lead to excessive heating and subsequent scorching of the plastic;

During routine production, plastic extruders occasionally experience scorching and inadequate plasticization. Now, the editors at Shuangda Machinery will analyze the underlying causes for our customers.

Plastic extruders are also a type of plastic machinery; they typically feed material into a cylindrical barrel and then extrude it using a screw.

After adopting variable-frequency drive technology, pressure can be precisely controlled, allowing for the selection of an appropriate linear speed. During production, extruders sometimes experience inadequate plasticization—what causes this?

I. Scorching

1. The phenomenon of scorching

(1) The temperature reading is excessively high, or the temperature‑control instrument has malfunctioned, resulting in overheating and scorching of the plastic.

(2) The glue outlet at the machine head produces heavy smoke, emits a strong odor, and is accompanied by crackling sounds.

(3) Granular scorch marks appear on the plastic surface;

(4) Continuous air pores are present on the exterior of the adhesive joint.

2. Causes of Scorching

(1) High temperature control leads to scorching of the plastic.

(2) Prolonged use of the screw without cleaning leads to the accumulation of charred residues, which are extruded along with the plastic.

(3) Prolonged heating causes plastic residues to undergo long-term thermal exposure, leading to aging, degradation, and scorching.

(4) Prolonged downtime without cleaning the die and screw resulted in thermal degradation and carbonization of the plastic.

(5) Frequent mold or color changes lead to plastic degradation and scorching.

(6) The gland at the machine head is not tightened, causing the plastic inside to age and decompose.

(7) The temperature control instrument malfunctioned, resulting in overheating and scorching of the coke.

3. Methods for Preventing Scorching

(1) Regularly check that the heating system is functioning properly;

(2) Regularly clean the screw or die head, ensuring thorough removal of any residue.

(3) Heat the material in accordance with process specifications; ensure the heating duration is not excessive. If there are any issues with the heating system, promptly notify the relevant personnel for resolution.

(4) Mold and color changes must be performed promptly and thoroughly to prevent color contamination or resin degradation due to overheating.

(5) After adjusting the mold, tighten the mold sleeve cover to prevent resin from entering.

(6) If scorching is detected, the die and screw should be cleaned.

II. Poor Plasticization

1. Phenomenon of poor plasticization

(1) The surface of the plastic layer exhibits a toad-skin-like texture.

(2) The temperature control is set too low; the instrument pointer indicates a low temperature, and the actual measured temperature is also low.

(3) The plastic surface has turned blackened and exhibits fine cracks or small particles that have not been properly plasticized;

(4) The plastic joint seam is poorly bonded, leaving a distinct visible mark.

2. Causes of Poor Plasticization

(1) The temperature control is too low or improperly set;

(2) The plastic contains resin particles that are difficult to plasticize;

(3) Improper operating procedures, with the screw and draw‑in speed set too high, result in incomplete plasticization.

(4) During granulation, the plastic may be unevenly mixed, or the plastic itself may have quality issues.