New topic about Aluminium extrusion die ,what is aluminium extrusion funnel?causes and corrective actions
1.What is aluminium extrusion funnel
Aluminium etrusion funnel is one special kind of defects.In the extrusion funnel it contains oxide,greasy dirt,and other defects from the billet surfaces.In the extrusion funnel part,there are cracks in the section，its mechanical property will not reach the starndards. We can check it by “Alkali Corrosion Inspection”,also we can find it by different colours on section through “Caustic Alkali Soaking”.
2.Three kinds of aluminium extrusion funnel
(1)Central funnel At the end of billet extruding,the rest of billet length is very short,the metal flow speed will increae at the centre of billet,faster than out layer,as a result hollow parts will happen in the centre. Oxide,lubricant and other dirts will fill in the hollow part,we call this centre funnel.
(2)Subcutaneous funnel At the end of billet extruding,the dead zone and palstic zone will move tempestuously.Maybe shearing deformation will happen and crack,Oxide,lubricant and other dirts will come out,also metal in dead zone will come out from the die,and stick under the surface of profiles.
(3)Annular funnel During the extruding period,near the dummy block and extrusion container,oxide and luricants will flow to the centre but not reach the centre,one annular funnel will appear.For this kind profiles,we can find a whole annular ring in the section.
3.Causes of aluminium extrusion funnel(mainly extrusion processing problem)
(1)the tailing billet length is very short;
(2)with oil or dirts in the dummy block;
(3)with dirty surface of aluminium billet;
(4)the end cutting length cannot meet requirements;
(5)The extrusion liner problem;
(6)suddenly speed up at the end of extruding.
(1)lower temp at the front of billet,use bulge shape of dummy block and reasonable length of tailing billet;
(2)clean toolings and surface of billet,or use billet peeling machine;
(3)regular inspection for extrusion container size and assembly;
(4)steady extrusion speed,lower speed at the end of extruding;
(5)According to regulations to cut two ends and butt shear,increase butt shear thickness;
(6)Change die design to improve metal flow(below 9 methods for reference)
If you have any question in working,welcome to share your experiences,we can find effective solution together.