A flow mark or halo,is a surface defect in which circular ripples or wavelets appear near the gate.
Ripples, a similar defect, appear as small fingerprint-like waves near the edge or at the end of the flow. It often shows as:

1. 1.Gloss Level difference compared to neighbored area;

2. 2.Unsmooth part shape transition.

The flow marks can be expected in the MF analying by checking:

Bulk temperature at the end of fill:a temperature drop of over 20 degree may get us the flow problem,An uniform bulk temperature distribution during filling is desirable for in MF stage of mold design;
Average velocity:High velocity values for a particular model section could indicate a high flow rate, meaning there could be filling problems such as overpacking or flash. This could also mean that polymer flow is unbalanced, where polymer flows fast through one section and flows slowly through another section of the part. the Max. value should be less than 27 for a bigger part and 15 for smaller part.

Causes

Material freezing near the gate. Low melt or mold temperature, and low ram speed can result in cold material entering the cavity. This can cause the partly solidified material to take on the form of the flow pattern.

Ripples caused by low temperature

a normal fountain flow with no ripples, b flow causing ripples (R).

Insufficient material compensation. Early gate freeze-off or low packing pressure may not pack the cavity properly. The material near the gate then freezes while maintaining the form of the flow pattern.

01.Confirming Part Data

02. The Overall Design,Mold Base and Settin

03.The Shape Forming Component

04.Feeding & Gating System

05. Undercut Releasing System

06. Ejection System

07.Supporting System

08. Cooling & Heating System

09. Venting

10. Hot Runner System

11.Safety Switch/Data Code/Hydraulic /pneumatic System