熱封時間主要由制袋(dai)機的速度決定。
速(su)度(du)(du)(du)(du)(du)快(kuai)，熱(re)(re)(re)(re)封(feng)(feng)時(shi)間就短；速(su)度(du)(du)(du)(du)(du)慢，熱(re)(re)(re)(re)封(feng)(feng)時(shi)間就長(chang)(chang)。熱(re)(re)(re)(re)封(feng)(feng)時(shi)間也是影(ying)響焊(han)縫(feng)(feng)封(feng)(feng)合強(qiang)度(du)(du)(du)(du)(du)和外(wai)觀(guan)(guan)的一個關鍵因(yin)素。相同的熱(re)(re)(re)(re)封(feng)(feng)溫(wen)(wen)度(du)(du)(du)(du)(du)和壓力(li)下，熱(re)(re)(re)(re)封(feng)(feng)時(shi)間長(chang)(chang)，則熱(re)(re)(re)(re)封(feng)(feng)層(ceng)熔合更充分，結合更牢固；但(dan)熱(re)(re)(re)(re)封(feng)(feng)時(shi)間太(tai)長(chang)(chang)，容易造成焊(han)縫(feng)(feng)起(qi)皺變形(xing)，影(ying)響平整(zheng)度(du)(du)(du)(du)(du)和外(wai)觀(guan)(guan)。熱(re)(re)(re)(re)封(feng)(feng)后的焊(han)縫(feng)(feng)若冷(leng)(leng)卻(que)不(bu)好，不(bu)但(dan)會影(ying)響焊(han)疑的外(wai)觀(guan)(guan)平整(zheng)度(du)(du)(du)(du)(du)，而且對熱(re)(re)(re)(re)封(feng)(feng)強(qiang)度(du)(du)(du)(du)(du)有一定(ding)的影(ying)響，冷(leng)(leng)卻(que)過(guo)程(cheng)就是通過(guo)在一定(ding)的壓力(li)下，用較(jiao)低的溫(wen)(wen)度(du)(du)(du)(du)(du)對剛(gang)熔融熱(re)(re)(re)(re)封(feng)(feng)后的焊(han)縫(feng)(feng)進(jin)行定(ding)形(xing)。因(yin)此，壓力(li)不(bu)夠，冷(leng)(leng)卻(que)和循環(huan)不(bu)暢，循環(huan)量不(bu)夠，水溫(wen)(wen)太(tai)高或冷(leng)(leng)卻(que)不(bu)及時(shi)，都會致使冷(leng)(leng)卻(que)不(bu)良，熱(re)(re)(re)(re)封(feng)(feng)強(qiang)度(du)(du)(du)(du)(du)降低。