US20180272580A1 - Insert to reduce weld line appearance defect in injection molding - Google Patents

Insert to reduce weld line appearance defect in injection molding Download PDF

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Publication number
US20180272580A1
US20180272580A1 US15/469,490 US201715469490A US2018272580A1 US 20180272580 A1 US20180272580 A1 US 20180272580A1 US 201715469490 A US201715469490 A US 201715469490A US 2018272580 A1 US2018272580 A1 US 2018272580A1
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US
United States
Prior art keywords
insert
molded part
mold cavity
melt
molten resin
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US15/469,490
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English (en)
Inventor
Jeffrey Kloberdanz
Liying Qi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ford Motor Co
Original Assignee
Ford Motor Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ford Motor Co filed Critical Ford Motor Co
Priority to US15/469,490 priority Critical patent/US20180272580A1/en
Assigned to FORD MOTOR COMPANY reassignment FORD MOTOR COMPANY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: QI, LIYING, Kloberdanz, Jeffrey
Priority to DE102018106744.5A priority patent/DE102018106744A1/de
Priority to CN201810245916.1A priority patent/CN108621368A/zh
Publication of US20180272580A1 publication Critical patent/US20180272580A1/en
Priority to US17/027,054 priority patent/US11938659B2/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/0025—Preventing defects on the moulded article, e.g. weld lines, shrinkage marks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B29C45/14065—Positioning or centering articles in the mould
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/0025—Preventing defects on the moulded article, e.g. weld lines, shrinkage marks
    • B29C2045/0032—Preventing defects on the moulded article, e.g. weld lines, shrinkage marks sequential injection from multiple gates, e.g. to avoid weld lines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/0058—Liquid or visquous
    • B29K2105/0067—Melt
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts

Definitions

  • the present disclosure relates to a method of manufacturing a part, and more specifically to an apparatus and method of reducing the appearance of surface weld lines formed from a molding process such as injection molding.
  • Injection molding is a common process for the manufacture of parts, for example, automotive interior parts. Injection molding generally involves heating a polymeric/plastic material (e.g., thermoplastic) in the form of pellets to create a molten material. This molten material flows through the injection molding equipment and is injected through one or more flow fronts to fill a mold. Once inside the mold, the molten material then cools and solidifies to form a desired part shape (which is the shape of a cavity, or multiple cavities within the mold).
  • a polymeric/plastic material e.g., thermoplastic
  • a quality and/or surface appearance issue for the consumer and/or the manufacturer arises where the molten materials join together within a mold cavity.
  • a break in molecular orientation of the molten materials may occur, therefore a line, a notch, and/or a color change can appear and form what is commonly referred to as a weld line, an example of which is shown in FIG. 1 .
  • the location of the weld line typically occurs in locations where the molten material does not bond perfectly or where there are holes or weak areas from different molten material flow fronts.
  • Weld lines may cause weak areas in the molded part, where the strength of the weld line can be from 10-90% of the molten materials. With a reduction in strength, when the location of the weld line is stressed, it can cause an undesirable fracture of the part.
  • Typical solutions to reducing weld lines include induction heating or “E-Mold” where the surface of the injection mold is brought to a super heated state to promote better bonding at the weld line locations.
  • E-Mold induction heating
  • a molded part that defines adjacent outer surfaces comprising at least one weld line extending between the adjacent outer surfaces.
  • An insert is disposed at the weld line and extends at an angle between the adjacent outer surfaces.
  • the insert is configured to improve molecular and fiber orientation to reduce the severity of the weld line on appearance and/or mechanical properties.
  • the insert is defined by a reverse-S cross-sectional geometry.
  • the insert may be a polymeric material
  • the molded part may be a single material
  • the molded part comprises at least two polymers and the insert is a material of one of the at least two polymers
  • the molded part comprises at least two polymers and the insert is a material that is different than the at least two polymers.
  • the molded part includes a plurality of weld lines and a corresponding plurality of inserts disposed at the plurality of weld lines, each insert extending at an angle between the adjacent outer surfaces of the molded part.
  • the molded part defines a thickness at the weld line, and the insert extends through at least 90% of the thickness.
  • the molded part may also be fiber-reinforced.
  • a method of forming a part comprises locating an insert at an angle within a mold cavity, sending a quantity of molten resin through the mold cavity to form a first melt front, and sending another quantity of molten resin through the mold cavity to form a second melt front, wherein the first melt front meets the second melt front at a weld line and each front flows along opposite sides of the insert.
  • the mold cavity defines opposed internal surfaces, and the insert is disposed at an angle between the internal surfaces at the weld line. One end of the insert may be fixedly located to one of the opposed internal surfaces, and another end of the insert floats within the mold cavity.
  • a plurality of inserts may be located at an angle within at least one mold cavity, and a plurality of quantities of molten resin are sent through the mold cavity to form a plurality of melt fronts, and the plurality of melt fronts meet adjacent melt fronts at a plurality of weld lines and each adjacent front flows along opposite sides of each insert.
  • the insert defines a material having a glass transition temperature greater than or equal to a glass transition temperature of each of the quantities of molten resin.
  • a method of injection molding a part comprises locating an insert at an angle within a mold cavity, injecting a quantity of molten resin through the mold cavity to form a first melt front, and injecting another quantity of molten resin through the mold cavity to form a second melt front, wherein the first melt front meets the second melt front at the insert and each front flows along opposite sides of the insert.
  • FIG. 1 is a perspective view of a molded part having a visible weld line according to the prior art
  • FIG. 2A is a progressive cross-sectional view illustrating a weld line being formed in a molding process according to the prior art
  • FIG. 2B is a progressive cross-sectional view illustrating weld line formation using an insert constructed according to the teachings of the present disclosure
  • FIG. 3A is a cross-sectional plot of a simulated average major modulus across a weld line according to the prior art
  • FIG. 3B is a cross-sectional plot of a simulated average major modulus across a weld line having an insert according to the teachings of the present disclosure.
  • FIG. 4 is a flow diagram illustrating a method of forming a part having an insert according to the principles of the present disclosure.
  • steps A through D illustrate progressive movement of molten materials within a mold over time.
  • a molding process e.g. injection molding
  • molten materials 11 a and 11 b flow towards each other in the direction of the arrows as shown, where the arrows represent the melt fronts of each of the molten materials 11 a / 11 b.
  • weld line 13 a line, notch and/or color change referred to as a weld line 13 .
  • a weld line 13 a line, notch and/or color change referred to as a weld line 13 .
  • multiple weld lines may occur in the molded part 10 .
  • the molded part 20 includes adjacent outer surfaces 22 and 24 (step D) and comprises at least one weld line 26 extending between the adjacent outer surfaces 22 and 24 .
  • the molded part 20 includes an innovative insert 30 , which is disposed at the weld line 26 and extends at an angle between the adjacent outer surfaces 22 and 24 of the molded part 20 .
  • the insert 30 defines a reverse-S cross-sectional geometry, however, it should be understood that other geometries for an insert that extend at an angle between the adjacent outer surfaces 22 and 24 may be employed while remaining within the scope of the present disclosure.
  • any angle may be employed provided that the insert 30 functions to reduce the visibility and/or mechanical impact of weld lines of molded parts, and thus the angle illustrated herein is merely exemplary. Further, a profile of the insert 30 (which would be in and out of the cross-section of FIG. 1B and along a surface of the molded part 20 ) mimics a surface contour of the final molded part 20 .
  • each of the materials 32 a and 32 b flows along opposite sides of the insert 30 as shown by the smaller arrows at the melt fronts.
  • the insert 30 functions to improve molecular and fiber orientation.
  • the severity of the weld line 26 is reduced, or in other words, the visibility of the weld line 26 at the outer surfaces 22 and 24 is reduced, and/or the mechanical impact of the weld line 26 is reduced, with the use of the insert 30 .
  • the insert 30 is a polymeric material, such as a thermoplastic or a thermoset.
  • the molded part 20 may be a single polymeric material, or the molded part 20 may be at least two polymers, wherein the insert 30 is a material of one of the at least two polymers. Alternately, when the molded part 20 comprises at least two polymers, the insert 30 may be a material that is different than the polymers of the molded part 20 . It should also be understood that a plurality of inserts 30 may be employed at a plurality of weld lines within the molded part 20 while remaining within the scope of the present disclosure.
  • the molded part 20 may also be fiber reinforced.
  • the insert 30 defines a material having a glass transition temperature greater than or equal to a glass transition temperature of each of the molten materials 32 a and 32 b.
  • the insert 30 is made of a material that will remelt with the final molded part 20 to homogenize as much as possible to reduce its surface appearance and/or any impact on mechanical properties of the final molded part 20 .
  • the insert 30 may be manufactured/formed by a 3D printing process. Alternately, the insert 30 itself may be molded.
  • the molded part 20 defines a thickness T at the weld line 26 .
  • the insert 30 extends through at least 90% of the thickness T. It should be understood, however, that the insert 30 may extend through various thicknesses, less than or greater than 90%, while remaining within the scope of the present disclosure.
  • the insert 30 is disposed at an angle between internal opposed surfaces 34 and 36 of the mold cavity 25 (step A).
  • the insert 30 may be secured by way of a tooling locating feature (e.g., notch, not shown) or may be secured to one or both of the opposed surfaces 34 / 36 prior to molding using another means.
  • the insert 30 is fixedly located to one of the opposed internal surfaces 34 / 36 , and another end of the insert 30 floats within the mold cavity 25 .
  • the insert 30 may entirely float within the mold cavity 25 , thus resulting in a weld line 26 that moves as a function of flow dynamics of each of the molten materials 32 a and 32 b.
  • the average major modulus of the part 10 without an insert is compared with an average major modulus of the part 20 with an insert 30 using computer aided engineering (CAE) simulations.
  • CAE computer aided engineering
  • FIG. 3A it is apparent that the weld line 13 has a much lower average major modulus and will result in a more visible weld line at the outer surfaces of the molded part 10 .
  • FIG. 3B the presence of an insert 30 increases the average major modulus at the weld line 26 , thus resulting in a less visible weld line at the outer surfaces and increased mechanical properties of the molded part 20 .
  • FIG. 4 a method of forming a part according to the teachings of the present disclosure is schematically illustrated.
  • an insert is located at an angle within a mold cavity.
  • a quantity of molten resin is sent through the mold cavity to form a first melt front
  • another quantity of molten resin is sent through the mold cavity to form a second melt front, wherein the first melt front meets the second melt front at a weld line and each front flows along opposite sides of the insert.
  • the method may be any molding process and in one form is injection molding. In this case, the the molten resin is injected through the mold cavity.
  • a plurality of inserts may be used within the mold cavity, each being disposed at an angle within the mold cavity.
  • a plurality of quantities of molten resin are sent through the mold cavity to form a plurality of melt fronts.
  • the plurality of melt fronts meets adjacent melt fronts at a plurality of weld lines and each adjacent front flows along opposite sides of each insert.
  • the molten resin may be a single polymeric material, or different polymeric materials may be used to form a single molded part. It should be understood that variations in materials for the molten resin and the insert may be varied and are considered to be within the scope of the present disclosure.
  • the location of the insert within a mold cavity may be determined either in tool trials and/or by CAE simulations.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
US15/469,490 2017-03-25 2017-03-25 Insert to reduce weld line appearance defect in injection molding Abandoned US20180272580A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US15/469,490 US20180272580A1 (en) 2017-03-25 2017-03-25 Insert to reduce weld line appearance defect in injection molding
DE102018106744.5A DE102018106744A1 (de) 2017-03-25 2018-03-21 Einsatz zum verringern eines mangels am erscheinungsbild einer schweissnaht beim spritzgiessen
CN201810245916.1A CN108621368A (zh) 2017-03-25 2018-03-23 减少注射成型中的熔接线外观缺陷的插入件
US17/027,054 US11938659B2 (en) 2017-03-25 2020-09-21 Insert to reduce weld line appearance defect in injection molding

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US15/469,490 US20180272580A1 (en) 2017-03-25 2017-03-25 Insert to reduce weld line appearance defect in injection molding

Related Child Applications (1)

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US17/027,054 Division US11938659B2 (en) 2017-03-25 2020-09-21 Insert to reduce weld line appearance defect in injection molding

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US15/469,490 Abandoned US20180272580A1 (en) 2017-03-25 2017-03-25 Insert to reduce weld line appearance defect in injection molding
US17/027,054 Active 2038-10-20 US11938659B2 (en) 2017-03-25 2020-09-21 Insert to reduce weld line appearance defect in injection molding

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US17/027,054 Active 2038-10-20 US11938659B2 (en) 2017-03-25 2020-09-21 Insert to reduce weld line appearance defect in injection molding

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CN (1) CN108621368A (de)
DE (1) DE102018106744A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022159972A1 (en) * 2021-01-21 2022-07-28 Okeanos Group, Llc Barrier film

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111300727B (zh) * 2020-02-25 2022-04-05 金发科技股份有限公司 一种聚合物的注塑方法和系统

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3991146A (en) * 1974-04-01 1976-11-09 Imperial Chemical Industries Limited Method of encapsulating an insert in plastics material by injection molding
WO2001024986A1 (en) * 1999-10-05 2001-04-12 Conix Corporation Injection molding techniques utilizing interlocking knit lines
US20010028949A1 (en) * 2000-01-31 2001-10-11 Yoshiaki Togawa Process for producing injection molded products

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050067084A1 (en) * 2003-09-03 2005-03-31 Kagan Val A. Method and article for evaluating and optimizing joined thermoplastic parts

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3991146A (en) * 1974-04-01 1976-11-09 Imperial Chemical Industries Limited Method of encapsulating an insert in plastics material by injection molding
WO2001024986A1 (en) * 1999-10-05 2001-04-12 Conix Corporation Injection molding techniques utilizing interlocking knit lines
US20010028949A1 (en) * 2000-01-31 2001-10-11 Yoshiaki Togawa Process for producing injection molded products

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022159972A1 (en) * 2021-01-21 2022-07-28 Okeanos Group, Llc Barrier film

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Publication number Publication date
DE102018106744A1 (de) 2018-09-27
US11938659B2 (en) 2024-03-26
US20210069950A1 (en) 2021-03-11
CN108621368A (zh) 2018-10-09

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