B\u00e0i vi\u1ebft d\u01b0\u1edbi \u0111\u00e2y s\u1ebd ph\u00e2n t\u00edch chi ti\u1ebft nguy\u00ean nh\u00e2n ph\u00e1t sinh Pit Mark v\u00e0 c\u00e1c gi\u1ea3i ph\u00e1p kh\u1eafc ph\u1ee5c hi\u1ec7u qu\u1ea3 trong qu\u00e1 tr\u00ecnh \u00e9p nh\u1ef1a<\/strong>.<\/p>\n Pit Mark (v\u1ebft r\u1ed7)<\/strong> l\u00e0 hi\u1ec7n t\u01b0\u1ee3ng xu\u1ea5t hi\u1ec7n c\u00e1c \u0111i\u1ec3m r\u1ed7 nh\u1ecf tr\u00ean b\u1ec1 m\u1eb7t s\u1ea3n ph\u1ea9m nh\u1ef1a<\/strong> sau qu\u00e1 tr\u00ecnh \u00e9p phun. C\u00e1c v\u1ebft r\u1ed7 n\u00e0y th\u01b0\u1eddng c\u00f3 k\u00edch th\u01b0\u1edbc kho\u1ea3ng 0.1 \u2013 0.5 mm<\/strong> v\u00e0 ph\u00e2n b\u1ed1 r\u1ea3i r\u00e1c tr\u00ean b\u1ec1 m\u1eb7t s\u1ea3n ph\u1ea9m.<\/p>\n Hi\u1ec7n t\u01b0\u1ee3ng n\u00e0y th\u01b0\u1eddng x\u1ea3y ra t\u1ea1i:<\/p>\n Nguy\u00ean nh\u00e2n ch\u00ednh c\u1ee7a Pit Mark l\u00e0 do nh\u1ef1a n\u00f3ng ch\u1ea3y kh\u00f4ng ti\u1ebfp x\u00fac ho\u00e0n to\u00e0n v\u1edbi b\u1ec1 m\u1eb7t khu\u00f4n (cavity)<\/strong> trong giai \u0111o\u1ea1n gi\u1eef \u00e1p (holding stage).<\/p>\n L\u1ed7i Pit Mark c\u00f3 th\u1ec3 nh\u1eadn bi\u1ebft th\u00f4ng qua m\u1ed9t s\u1ed1 \u0111\u1eb7c \u0111i\u1ec3m sau:<\/p>\n Nh\u1eefng s\u1ea3n ph\u1ea9m y\u00eau c\u1ea7u cao v\u1ec1 ngo\u1ea1i quan nh\u01b0 linh ki\u1ec7n \u0111i\u1ec7n t\u1eed, v\u1ecf thi\u1ebft b\u1ecb, s\u1ea3n ph\u1ea9m gia d\u1ee5ng<\/strong> th\u01b0\u1eddng r\u1ea5t d\u1ec5 b\u1ecb \u1ea3nh h\u01b0\u1edfng b\u1edfi l\u1ed7i n\u00e0y.<\/p>\n Sau khi nh\u1ef1a n\u00f3ng ch\u1ea3y \u0111\u01b0\u1ee3c phun v\u00e0o khu\u00f4n, b\u1ec1 m\u1eb7t s\u1ea3n ph\u1ea9m s\u1ebd \u0111\u00f4ng c\u1ee9ng tr\u01b0\u1edbc<\/strong>, trong khi ph\u1ea7n l\u00f5i b\u00ean trong v\u1eabn c\u00f2n \u1edf tr\u1ea1ng th\u00e1i n\u00f3ng ch\u1ea3y<\/strong>.<\/p>\n N\u1ebfu \u00e1p l\u1ef1c gi\u1eef kh\u00f4ng \u0111\u1ee7<\/strong>, nh\u1ef1a b\u00ean trong s\u1ebd co r\u00fat<\/strong> v\u00e0 kh\u00f4ng th\u1ec3 \u00e9p s\u00e1t v\u00e0o b\u1ec1 m\u1eb7t khu\u00f4n. Khi \u0111\u00f3, l\u1edbp b\u1ec1 m\u1eb7t b\u00e1n \u0111\u00f4ng c\u1ee9ng (semi-solidified layer) kh\u00f4ng ti\u1ebfp x\u00fac ho\u00e0n to\u00e0n v\u1edbi cavity, d\u1eabn \u0111\u1ebfn h\u00ecnh th\u00e0nh v\u1ebft r\u1ed7 tr\u00ean b\u1ec1 m\u1eb7t s\u1ea3n ph\u1ea9m<\/strong>.<\/p>\n \u0110\u00e2y \u0111\u01b0\u1ee3c xem l\u00e0 nguy\u00ean nh\u00e2n ph\u1ed5 bi\u1ebfn nh\u1ea5t g\u00e2y ra Pit Mark<\/strong>.<\/p>\n Khi nhi\u1ec7t \u0111\u1ed9 nh\u1ef1a (Resin Temperature)<\/strong> ho\u1eb7c nhi\u1ec7t \u0111\u1ed9 khu\u00f4n (Mold Temperature)<\/strong> qu\u00e1 th\u1ea5p:<\/p>\n K\u1ebft qu\u1ea3 l\u00e0 nh\u1ef1a kh\u00f4ng l\u1ea5p \u0111\u1ea7y ho\u00e0n to\u00e0n b\u1ec1 m\u1eb7t khu\u00f4n<\/strong>, t\u1ea1o ra c\u00e1c \u0111i\u1ec3m r\u1ed7 nh\u1ecf.<\/p>\n N\u1ebfu v\u1eadt li\u1ec7u nh\u1ef1a c\u00f3 \u0111\u1ed9 ch\u1ea3y k\u00e9m<\/strong>:<\/p>\n \u0110i\u1ec1u n\u00e0y d\u1ec5 d\u1eabn \u0111\u1ebfn s\u1ef1 h\u00ecnh th\u00e0nh Pit Mark tr\u00ean b\u1ec1 m\u1eb7t s\u1ea3n ph\u1ea9m<\/strong>.<\/p>\n T\u1ed1c \u0111\u1ed9 \u00e9p phun qu\u00e1 th\u1ea5p c\u00f3 th\u1ec3 g\u00e2y ra:<\/p>\n Do \u0111\u00f3, Pit Mark c\u00f3 th\u1ec3 xu\u1ea5t hi\u1ec7n t\u01b0\u01a1ng t\u1ef1 nh\u01b0 tr\u01b0\u1eddng h\u1ee3p nh\u1ef1a c\u00f3 \u0111\u1ed9 ch\u1ea3y k\u00e9m<\/strong>.<\/p>\n \u0110\u00e2y l\u00e0 gi\u1ea3i ph\u00e1p hi\u1ec7u qu\u1ea3 nh\u1ea5t \u0111\u1ec3 kh\u1eafc ph\u1ee5c Pit Mark.<\/p>\n Khi t\u0103ng Holding Pressure<\/strong>, nh\u1ef1a n\u00f3ng ch\u1ea3y s\u1ebd:<\/p>\n Tuy nhi\u00ean, c\u1ea7n l\u01b0u \u00fd r\u1eb1ng \u00e1p l\u1ef1c gi\u1eef qu\u00e1 cao c\u00f3 th\u1ec3 g\u00e2y ra c\u00e1c l\u1ed7i kh\u00e1c nh\u01b0 Flash (bavia)<\/strong>.<\/p>\n Ngo\u00e0i vi\u1ec7c t\u0103ng Holding Pressure, c\u00f3 th\u1ec3 \u00e1p d\u1ee5ng c\u00e1c bi\u1ec7n ph\u00e1p sau:<\/p>\n Gi\u00fap nh\u1ef1a ch\u1ea3y t\u1ed1t h\u01a1n<\/strong> v\u00e0 duy tr\u00ec tr\u1ea1ng th\u00e1i n\u00f3ng ch\u1ea3y l\u00e2u h\u01a1n.<\/p>\n L\u00e0m ch\u1eadm qu\u00e1 tr\u00ecnh \u0111\u00f4ng \u0111\u1eb7c b\u1ec1 m\u1eb7t.<\/p>\n Gi\u00fap \u0111i\u1ec1n \u0111\u1ea7y khu\u00f4n nhanh h\u01a1n<\/strong> v\u00e0 gi\u1ea3m \u0111\u00f3ng b\u0103ng s\u1edbm c\u1ee7a b\u1ec1 m\u1eb7t.<\/p>\n Cho ph\u00e9p \u00e1p l\u1ef1c gi\u1eef truy\u1ec1n v\u00e0o cavity hi\u1ec7u qu\u1ea3 h\u01a1n<\/strong>.<\/p>\n Gi\u1ea3m s\u1ef1 ch\u00eanh l\u1ec7ch gi\u1eefa c\u00e1c v\u00f9ng d\u00e0y v\u00e0 m\u1ecfng.<\/p>\n Ch\u1ecdn lo\u1ea1i nh\u1ef1a c\u00f3 MFI cao h\u01a1n<\/strong> \u0111\u1ec3 c\u1ea3i thi\u1ec7n kh\u1ea3 n\u0103ng \u0111i\u1ec1n \u0111\u1ea7y.<\/p>\n \u0110\u1ec3 h\u1ea1n ch\u1ebf Pit Mark trong s\u1ea3n xu\u1ea5t h\u00e0ng lo\u1ea1t, doanh nghi\u1ec7p n\u00ean:<\/p>\n Vi\u1ec7c ki\u1ec3m so\u00e1t t\u1ed1t c\u00e1c y\u1ebfu t\u1ed1 tr\u00ean s\u1ebd gi\u00fap gi\u1ea3m \u0111\u00e1ng k\u1ec3 l\u1ed7i Pit Mark v\u00e0 n\u00e2ng cao ch\u1ea5t l\u01b0\u1ee3ng s\u1ea3n ph\u1ea9m \u00e9p nh\u1ef1a<\/strong>.<\/p>\n
\n1. Pit Mark l\u00e0 g\u00ec?<\/h2>\n
![\"https:\/\/www.intouch-quality.com\/hs-fs\/hubfs\/img\/post_body_images\/injection-molding-defects-flow-lines.jpg?name=injection-molding-defects-flow-lines.jpg&width=320\"](\"https:\/\/www.intouch-quality.com\/hs-fs\/hubfs\/img\/post_body_images\/injection-molding-defects-flow-lines.jpg?name=injection-molding-defects-flow-lines.jpg&width=320\")
<\/div>\n<\/div>\n<\/div>\n![\"https:\/\/static.wixstatic.com\/media\/801a25_dc10862486ab457383890fb8884ba4a8~mv2.jpg\/v1\/fill\/w_960%2Ch_360%2Cal_c%2Clg_1%2Cq_80\/801a25_dc10862486ab457383890fb8884ba4a8~mv2.jpg\"](\"https:\/\/static.wixstatic.com\/media\/801a25_dc10862486ab457383890fb8884ba4a8~mv2.jpg\/v1\/fill\/w_960%2Ch_360%2Cal_c%2Clg_1%2Cq_80\/801a25_dc10862486ab457383890fb8884ba4a8~mv2.jpg\")
<\/div>\n<\/div>\n<\/div>\n![\"https:\/\/www.protolabs.com\/media\/qtjnlfrx\/im_defects_drag-marks_lr.jpg?height=308&v=1d9faa9147b1d10&width=570\"](\"https:\/\/www.protolabs.com\/media\/qtjnlfrx\/im_defects_drag-marks_lr.jpg?height=308&v=1d9faa9147b1d10&width=570\")
<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n
\n2. Bi\u1ec3u hi\u1ec7n c\u1ee7a l\u1ed7i Pit Mark<\/h2>\n
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\n3. Nguy\u00ean nh\u00e2n ph\u00e1t sinh Pit Mark<\/h1>\n
3.1 \u00c1p l\u1ef1c gi\u1eef kh\u00f4ng \u0111\u1ee7 (Holding Pressure Too Low)<\/h2>\n
\n3.2 Nhi\u1ec7t \u0111\u1ed9 nh\u1ef1a v\u00e0 nhi\u1ec7t \u0111\u1ed9 khu\u00f4n qu\u00e1 th\u1ea5p<\/h2>\n
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\n3.3 Kh\u1ea3 n\u0103ng ch\u1ea3y c\u1ee7a nh\u1ef1a th\u1ea5p (Poor Flowability)<\/h2>\n
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\n3.4 T\u1ed1c \u0111\u1ed9 phun th\u1ea5p (Low Injection Speed)<\/h2>\n
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\n4. Gi\u1ea3i ph\u00e1p kh\u1eafc ph\u1ee5c l\u1ed7i Pit Mark<\/h1>\n
4.1 T\u0103ng \u00e1p l\u1ef1c gi\u1eef (Holding Pressure)<\/h2>\n
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\u00c1p l\u1ef1c gi\u1eef khuy\u1ebfn ngh\u1ecb cho m\u1ed9t s\u1ed1 lo\u1ea1i nh\u1ef1a<\/h3>\n
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\n \nV\u1eadt li\u1ec7u nh\u1ef1a<\/th>\n Holding Pressure<\/th>\n Th\u1eddi gian gi\u1eef<\/th>\n<\/tr>\n<\/thead>\n \n Duracon (POM)<\/td>\n 59 \u2013 98 MPa<\/td>\n Gate sealing + 1\u20132 s<\/td>\n<\/tr>\n \n Duranex (PBT)<\/td>\n 59 \u2013 98 MPa<\/td>\n Gate sealing + 1\u20132 s<\/td>\n<\/tr>\n \n Fortron (PPS)<\/td>\n 36 \u2013 69 MPa<\/td>\n Gate sealing + 1\u20132 s<\/td>\n<\/tr>\n \n Vectra (LCP)<\/td>\n 29 \u2013 49 MPa<\/td>\n Gate sealing + 1\u20132 s<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
\n4.2 C\u00e1c \u0111i\u1ec1u ki\u1ec7n c\u00f3 th\u1ec3 c\u1ea3i thi\u1ec7n \u00e1p l\u1ef1c gi\u1eef<\/h2>\n
1. T\u0103ng nhi\u1ec7t \u0111\u1ed9 nh\u1ef1a<\/h3>\n
2. T\u0103ng nhi\u1ec7t \u0111\u1ed9 khu\u00f4n<\/h3>\n
3. T\u0103ng t\u1ed1c \u0111\u1ed9 phun<\/h3>\n
4. M\u1edf r\u1ed9ng k\u00edch th\u01b0\u1edbc Gate<\/h3>\n
5. \u0110i\u1ec1u ch\u1ec9nh chi\u1ec1u d\u00e0y th\u00e0nh s\u1ea3n ph\u1ea9m<\/h3>\n
6. S\u1eed d\u1ee5ng v\u1eadt li\u1ec7u c\u00f3 \u0111\u1ed9 ch\u1ea3y t\u1ed1t<\/h3>\n
\n5. C\u00e1ch ph\u00f2ng ng\u1eeba Pit Mark trong s\u1ea3n xu\u1ea5t<\/h1>\n
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