熱封(feng)時間主要由制袋機的速度決定。
速(su)度(du)(du)(du)快，熱(re)封(feng)(feng)(feng)時(shi)間就短(duan)；速(su)度(du)(du)(du)慢，熱(re)封(feng)(feng)(feng)時(shi)間就長(chang)。熱(re)封(feng)(feng)(feng)時(shi)間也是影(ying)(ying)響(xiang)焊縫(feng)封(feng)(feng)(feng)合(he)(he)強度(du)(du)(du)和外(wai)觀(guan)的一(yi)個(ge)關鍵因(yin)素。相同的熱(re)封(feng)(feng)(feng)溫度(du)(du)(du)和壓力下，熱(re)封(feng)(feng)(feng)時(shi)間長(chang)，則熱(re)封(feng)(feng)(feng)層熔合(he)(he)更(geng)充分，結合(he)(he)更(geng)牢固；但熱(re)封(feng)(feng)(feng)時(shi)間太(tai)長(chang)，容易造(zao)成焊縫(feng)起皺變形，影(ying)(ying)響(xiang)平整(zheng)度(du)(du)(du)和外(wai)觀(guan)。熱(re)封(feng)(feng)(feng)后(hou)的焊縫(feng)若(ruo)冷(leng)(leng)卻(que)(que)不(bu)好，不(bu)但會(hui)影(ying)(ying)響(xiang)焊疑(yi)的外(wai)觀(guan)平整(zheng)度(du)(du)(du)，而且對熱(re)封(feng)(feng)(feng)強度(du)(du)(du)有一(yi)定的影(ying)(ying)響(xiang)，冷(leng)(leng)卻(que)(que)過程就是通過在一(yi)定的壓力下，用較低(di)的溫度(du)(du)(du)對剛(gang)熔融熱(re)封(feng)(feng)(feng)后(hou)的焊縫(feng)進行(xing)定形。因(yin)此，壓力不(bu)夠，冷(leng)(leng)卻(que)(que)和循環(huan)不(bu)暢，循環(huan)量不(bu)夠，水溫太(tai)高(gao)或(huo)冷(leng)(leng)卻(que)(que)不(bu)及時(shi)，都會(hui)致使冷(leng)(leng)卻(que)(que)不(bu)良，熱(re)封(feng)(feng)(feng)強度(du)(du)(du)降低(di)。