英语翻译After die approval,it is positioned in the press and hea

英语翻译
After die approval,it is positioned in the press and heated.A die lubricant must be used for aluminum forging because the metal dose not form a scale as in the case of steel.Direct metal-to-metal contact can cause galling,rejected parts,and short die life.
Usually a preheated billet is placed in the die(some require preshaping).For aluminum,the billets are heated to about 800℉(425℃)and the die temperature is held at700°to750℉(370°to400℃)to ensure optimum metal flow.
The billet is held in place in the die by a hold-down ring.The part is lubricated and the press is cycled.The forging is removed form the press,and any major flash is removed by bandsawing and grinding.It is then reforged in the same die.The process may be repeated two to four times for final shaping.After trimming and cleaning,the finished forging is tested for integrity and hardness.