熱(re)封時間主要由制袋機的(de)速(su)度(du)決定。
速度(du)快，熱(re)(re)封(feng)(feng)(feng)(feng)時(shi)(shi)間(jian)就(jiu)短；速度(du)慢，熱(re)(re)封(feng)(feng)(feng)(feng)時(shi)(shi)間(jian)就(jiu)長(chang)。熱(re)(re)封(feng)(feng)(feng)(feng)時(shi)(shi)間(jian)也是影(ying)響焊(han)縫(feng)封(feng)(feng)(feng)(feng)合強度(du)和(he)外觀(guan)(guan)的(de)一(yi)個關鍵因素。相同的(de)熱(re)(re)封(feng)(feng)(feng)(feng)溫(wen)度(du)和(he)壓(ya)力下，熱(re)(re)封(feng)(feng)(feng)(feng)時(shi)(shi)間(jian)長(chang)，則熱(re)(re)封(feng)(feng)(feng)(feng)層熔(rong)合更充分，結合更牢固；但熱(re)(re)封(feng)(feng)(feng)(feng)時(shi)(shi)間(jian)太長(chang)，容易(yi)造成(cheng)焊(han)縫(feng)起(qi)皺變形，影(ying)響平(ping)整度(du)和(he)外觀(guan)(guan)。熱(re)(re)封(feng)(feng)(feng)(feng)后的(de)焊(han)縫(feng)若冷(leng)卻不(bu)好，不(bu)但會影(ying)響焊(han)疑的(de)外觀(guan)(guan)平(ping)整度(du)，而且對熱(re)(re)封(feng)(feng)(feng)(feng)強度(du)有一(yi)定(ding)的(de)影(ying)響，冷(leng)卻過(guo)程(cheng)就(jiu)是通(tong)過(guo)在一(yi)定(ding)的(de)壓(ya)力下，用(yong)較(jiao)低的(de)溫(wen)度(du)對剛熔(rong)融(rong)熱(re)(re)封(feng)(feng)(feng)(feng)后的(de)焊(han)縫(feng)進行定(ding)形。因此，壓(ya)力不(bu)夠，冷(leng)卻和(he)循環不(bu)暢，循環量不(bu)夠，水溫(wen)太高或(huo)冷(leng)卻不(bu)及時(shi)(shi)，都會致使冷(leng)卻不(bu)良，熱(re)(re)封(feng)(feng)(feng)(feng)強度(du)降低。