Injection mold designers must always take into consideration the surface finish required of the finished molded part. The ejection system in the mold that removes the solidified parts out of the mold cavity or cavities has great impact on the part’s surface finish. The most common ejection system uses ejector pins which can leave marks on the part, often referred to as witness lines.
An experienced mold designer will position ejector pins in order to place witness lines in an area acceptable to the part print. The ejection system and ejector pins are housed in the B side of the mold, extending into the cavity during ejection then retracting back into the mold. Restrictions on ejection must be apparent prior to mold design, if ejector pins cannot be used without damaging the part, lifters can be utilized for proper ejection. The injection mold design must correspond to the ejection pattern and stroke of the press. Michiana Global Mold is an experienced injection mold maker with in-depth knowledge of designing various ejection systems to meet customer specifications. We use CAD/CAM Unigraphics software to design and develop a layout for the ejection system prior to cutting steel. In some cases, ejection systems must be designed around robotic arms that reach into grab the parts upon ejection. These robotic systems are called ‘sprue pickers’, as sprue is another term for the runner that is also ejected with the part. Some ejection systems automatically separate parts and runners, so that they do not need to be separated later. Whatever your part design, surface finish, or ejection system is required, Michiana Global Mold will design and construct a superior mold with flawless ejection for the specified part surface finish. We are an ISO registered mold making company with an offshore mold making partner in China. Contact us today for a FREE design consultation and to speak with a skilled mold engineer.
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When an injection mold designer begins a development of the mold design, they must be aware of the environment in which the mold will run. This includes the size and type of press the mold will run in, the material used for molding, and any auxiliary equipment used for automation as the location of tie bars and cooling lines must not interfere with setting and running the mold.
Vacuum Conveying System A vacuum conveying system is an automated way to get the material into the press, with the right suction and force. Vacuum conveying systems suck the material while still in pellet from the gaylord or drum into the hopper of the press, providing a steady flow of material for continuous production. Vacuum conveying systems pull in a steady flow of material, and control the amount of material in flow to the press, and are also helpful with controlling the moisture content in the material. Sprue Pickers Aid Automation Sprue pickers are robotic arms that reach into the press and grab the runner when the mold ejects, instantly separating from it the parts which can then fall into a bucket or onto a conveyor belt. Some robotic sprue pickers reach in and pick up the runner then drop it either into a separate bin, or directly into a grinder where it can be ground up and reused as regrind material. Process Monitoring Injection molders use process monitoring systems to constantly monitor the press settings such as temperature and pressure, alerting an operator if the job begins to run out of specification. Some monitoring systems also provide material resource planning functions, tracking job due dates and material inventory for scheduling of jobs. All of the additional auxiliary equipment must function properly and work in conjunction with the mold when it opens and closes and operates on the tie bar. Michiana Global Mold has vast experience designing and manufacturing molds adhering to customer specifications and each unique environment. Contact us today for a FREE design consultation and to learn how we can assist. Production injection molds are used to mass produce plastic injection molded parts. Injection molding is the producing of specially designed plastic parts by injecting with pressure and clamp force, plastic in a molten state into cavities carved out in a steel mold where the plastic will harden and set to the shape of the mold, thus producing the part.
Injection mold makers sometimes produce a prototype tool to test out a part design and function prior to manufacturing full production requirements. Production molds are used for long term production requirements. A prototype tool is used only for short runs to produce sample parts for testing and will not support full production. With proper planning and mold design, a custom mold maker will design and manufacture a production mold that will meet all product specifications and geometric dimensions. Some of these dimensions must be met with the tightest of tolerances as close as .001”, or about the width of a human hair. Carving out the cavities of a steel mold to produce a plastic part within these tight tolerances is no easy task, especially when taking into consideration the properties of the thermoplastic resin including cooling and shrink rate, which can have a great effect on the final dimensions of the part after solidifying. If a change is required of a production mold, skilled mold makers can perform what is called an “engineering change” to alter a dimension or tolerance within a part. If the change is feasible just by altering some dimensions in the steel, mold makers can simply adjust some dimensions in the current tool and avoid the need of constructing a new mold altogether. Skilled and experienced mold makers will utilize advanced quality product planning procedures to ensure that the constructed production mold will produce parts to spec the first time, planning ahead for critical fill areas and ensuring parts to print. Michiana Global Mold is an experienced full-service tool and die shop, constructing high performing injection molds with quality steel. We are an ISO registered mold making facility, applying our strict quality policies in all processes. Contact us today for a FREE design consultation and to see how we can assist with your next injection mold production requirements. Prototype injection molds provide a chance to perfect the design of a molded product, prior to constructing a full size multi-cavity tool. This can be well worth the extra time and expense to make a smooth launch of mass production requirements.
A prototype mold is a very inexpensive method of testing out a new part design for proper functioning. Prototypes are usually constructed with less expensive material such as non-hardened steel or P20, or even aluminum, as the purpose is to mold sample lots of parts, not full production volume. A prototype mold usually has just one cavity, and this can be an easy to way to make sure a part will work as expected, before manufacturing a large multi-cavity tool. One part is all that is needed to verify the part’s dimensions and geometric tolerances. A prototype mold is used in industries where new model parts are always changing such as the Automotive industry. In some cases, new parts are used in existing assemblies, changing a design slightly but still using some existing components. In this case the new parts would have to be tested within the existing assemblies to ensure proper function. Prototypes give automotive design engineers a chance to try out a new part, and alter it if need be, to work properly with other new or existing components. Prototype Mold Advantages In addition to the flexibility to try out new part designs to verify part function, the biggest advantage of prototype tools is the low cost. Made with the less sturdy and less expensive material, a prototype tool cannot support production, it can however provide enough shots to produce sample parts for testing purposes. This is a very worthwhile investment, however, especially if you are uncertain about how the geometric design on one part will fit with your existing application, or if you just want to test part properties prior to building a production mold. With the low cost of prototype tools, it could be a very advantageous place to start here if you have any questions about a new part function. A prototype is also advantageous if the part is molded with a new resin, or a resin that the engineer is not familiar or experienced with. Since all thermoplastic resins contain varying properties for shrink rate, strength and durability, some prototypes are constructed to test the strength of a molded part in different materials allowing engineers to test out different resins. Michiana Global Mold has vast experience constructing prototype tools to customer specifications, giving you a quick turn-around time on sample parts for your testing purposes. We employ skilled design engineers and journeyman mold makers all with in-depth knowledge of prototype mold construction, and properties of varying resins. Michiana Global Mold has vast experience assisting engineers and designers to achieve their dimensional goals with design assistance and Prototype Mold Construction. Contact us today for a free design consultation and to see how we can assist you with your project development goals. |
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