• Two shot injection mold design consideration

    This article discusses basic consideration for designing two-shot injection molds, which is referred to also as dual-shot, dual-injection, double-shot, double-injection, multi-shot, 2k molding, and overmolding Before tool design, one should check machine injection unit Injection unit sometimes constrain the tooling type. Material shrinkages for each material should be considered. Shrinkage may cause warpage and flash if those are not made up properly in tooling phase. If there is big different in melt temperature between materials, toolheat balancing should be .studied Tooling should consider gate location, access, allowable gate vestige. Draft angle in 2K molding is very critical factor which deciding wheremolded part stuck and rotating. In 1st shot molding, molded part should be stuck on rotating core and 2nd shot molding, molded part should remain on the side of ejecting system employed.   If part design imposing creating shut-off surface with molded part after rotating,Draft angle on shut-off surface should be…

    Mold design January 13, 2020
  • How to fix defects on double injection molding

    This article mainly discusses some of the molding defects that can occur in a part during the process of double injection molding, and ways to fix and avoid them.    Flash Description –2nd material penetrating between 1st material and its’ It observed frequently where 1st material shrinkage is big and cooling time for 1material is too long. It is mainly due to too fast shrinking of 1stmaterial. Optimizing holding pressure & Cooling time to get min shrinking of 1stmaterial till before 2nd shot Select less shrinkage ratematerial for 1st Changing design as preventive Rainbow Description – Because of too high melt temperature or shear, 1st molded material remelt and flow with 2nd § Solution   Lower 2nd material melt temperature or minimize Use low melt resin or low viscosity material as 2nd Changing the sequence of material.( Clear – 1st shot, Opaque- 2nd shot) Washout Description – Because of too high melt temperature or shear,…

    Mold making, Uncategorized January 11, 2020
  • Part design guidelines on double injection molding

    In this article, we will show you from three aspects to be taken into consideration when designing plastic parts for double injection molding so we can save our customers time and money in the long run.   Mechanical structure     Surface Contact Adhesion is depending on materials compatibility, process temperatures, surface contact area, molding sequence and designing of mechanical interlock systems. If design not allows enough contact surface area, Tooling can make up like Make-up 1 : Increase expose surface byincreasingroughness. Make-up 2 : Employ interlock Wall Thickness Utilize 2nd shot to get more uniform wallthickness  Reinforce the 1st  and 2nd shot(transparent) by structure design such as “H” section etc. Thin but high rib in 2nd short. First shot thicker than 2nd shot. 2nd shot should be as thin as possiblewhen flow and weld line is not a issue. In MP case, 1st shot 0.6mm, 2nd shot 0.6mm was made Avoid sharpcorner Make…

    Mold design January 10, 2020
  •  Guidelines on Insert Molding

    What is Insert Molding? Insert molding is a process of fabricating a finished part by applying a metal part into  moltenres in a mold. As compared to installing inserts into a plastic molded part in a post-molding process, the use of molded-in inserts eliminates the need for secondary installation of the inserts and thereby reduces costs. The mold temperature of INSERT MOLDING process is 65 -120 cels degree, and the material temperature is 260-320 cels degrees. Of course, different raw material ratios have different temperature ranges requirment and the resin producer will provide upper and lower limit temperature with the datasheet.   The upper limit temperature indicates the temperature at which the material begins to carbonize and decompose, while the lower limit temperature indicates the temperature at which the material begins to flow.On one hand, if the molten temperature is lower than the lower limit, the liquidity of the material is insufficient, and the insufficient plasticity of the molding screw can easily break the molding…

    Uncategorized January 9, 2020
  • Injection Mold Design Basics  

    Plastic injection mold is the foundation of the success of  custom plastic part and we mainly discuss the design basics  you need to know when developing your plastic project in this series of articles. Designing plastic injection mold for manufacturability is the first step in making a high-quality part. Before start, we need to understand what is the standard of a well-designed mold.  The basic function of a mold is two fold. Firstly it should impart shape to the part secondly it should cool the molded part. The number of cavities mainly depends up on the production volume requirement. But it is also related to the size and weight of the parts which in turn determines the machine capacity required. It is also important to design a mold that will safely absorb the forces of clamping, injection and ejection. Further more the mold lay out should be balanced which will ensure proper filling and…

    Mold design January 8, 2020
  • How to define number of cavities in a plastic injection mold?

    When it comes to cavity number for a plastic injection mold, there is a lot to be considered by injection molder though usually the number of cavities is decided by the customer.  Please note the following:   The most important thing to consider is the size of the part and how complext. Does the part have a lot of slides,lifters, core pulls etc. Size of press that the mold is going to run in, how many tons in the press rated for, what’s the platen size, and what’s the shot size. What is total quantity of the part? all you must consider delivery time on the parts. If you have a tight just in time delivery schedule that will also determine the amount of cavities needed to support the timing. What is the target cycle time? How is the resin going to be distributed within the mold? surface runner, insulated…

    Mold making January 7, 2020
  • Design Fan Gate In Injection Mold

    What is fan gate? Fat gate, namely ,the shape of the gate looks like a fan.Fan gate is usually used on multi-cavity molds or two-plate molds. It is a common edge gate located located in the sidewalll of the part to prevent restriction of resin flow. Since the gate could distribute melt resin into the cavity more evenly, thus it is normally applicable to parts that require a high degree of flatness and absence of flow lines. It also minimizes the possibility of part warpage and helps to maintain dimensional stability.     From above pictures we could see that the fan gate has shortcomings as well. Since the gate is too wide and it may increase labor cost  to degate after molding. Besides the gate is long leaving visible trimming mark, it may affect cosmetic look as well. And there is high potentiality for air entrapment if not carefully…

    Mold making January 6, 2020
  • How to Troubleshoot Flash Defect on Two Shot Injection Molding 

    What is flash in two shot injection molding? Description  2nd material penetrating between 1st material and its cavity. It is observed frequently where 1st material shrinkage is big and cooling time for 1  material is too long. It is mainly due to too fast shrinking of 1st material.   How to trouble shoot the flash? 1.Optimizing holding pressure & Cooling time to get min shrinking of 1st material till before 2nd shot molding. 2.Select less shrinkage rate material for 1st shot. 3.Changing design as preventive action. We’ve spent the past 15 years accumulating rich practical experience in solving the flash of two-shot injection molding. HS Mold has the design, engineering, and in-house tooling capabilities you need to streamline your project 2k injection molding project from conception to production.              

    Injection molding process January 3, 2020
  • Soft Tooling VS Hard Tooling

    What is soft tooling? Soft tooling, or prototype mold is preferred when we need injection molded parts quickly or at a lower cost.  It is also great choice for low volumes. We can use soft steel such as NAK80 or  aluminum to build the soft mold in house. Once the mold has been completed,  we can make your parts in-house using our ton injection molding machine ranging from 50Ton to 650Ton.  The soft tooling is featured as below.   The tooling inserts are made using 718 HH or Nak 80, (preharden 33 to 38 HRC). Inserts can be drilled, milledand grindedusing normal process of machining. The tool life is guarantee up to 500 K shotwhile aluminium mold up to 10K shots. The lead time is shorter compare to hard tool. For Proto Tool or toolingwith low volume requirement. What is hard tooling? Hard tool is production tooling that requires high quality . The core and cavity is usually made of the…

    Mold making January 2, 2020
  • Everything you need to know about hot runner mold for engineering polymers

    When injection moulding partially crystalline engineering thermoplastics, choice of the correct hot runner system determines the function of the plastic injection mould and moulded part quality. Here, the temperature must be controlled much more strictly than in the case of amorphous materials. The type of hot runner system used,  and its installation, decide the properties of the finished parts. This article deals with the most important points which have to be considered when choosing the most suitable hot runner system for POM (acetal), PA (nylon), PBT and PET (polyesters). Problems with hot runners Moisture in thegranules Feed system toosmall Wrong gateposition Hold time tooshort Wrong melttemperature Wrong tooltemperature Poor surfacefinish Problems with hotrunners Warpage Moulddeposit   What happens when an unsuitable hot runner system is used? Unsuitable hot runner systems usually cause high pressure losses; they should, if used at all, be operated only at very high temperatures. This will usually cause the polymer to degrade, with…

    Mold design, Mold making January 1, 2020