Oct 18, 2019
Even originally used to describe a long thin slat in shipbuilding, the term spline is nowadays used in connection with CAD systems.
In mathematics, a spline is a smooth curve, which runs through (or near) a series of points. These points (also called control points) influence the shape of the resulting spline curve.
If a spline curve can be described in all sections using a linear function, the spline is also called polygon or linear spline.
Similarly, square or cubic splines can be found.
In CAD systems mostly Non-Uniform Rational B-Splines (NURBS) are used for the representation of a curve. Based on spline curces spline surfaces can be created.
For them the term free-form surfaces is very often used. Free form surfaces are needed in particular in automotive engineering.
General: Spline curve with control points created in a
CAD system
Related topics:
Computer Aided Manufacturing (
CAM)
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This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Jan 28, 2019
In the injection molding process, the melt is guided from the machine nozzle into the sprue bushing and further into the runner system or the cavity.
The machine nozzle is pressed against the sprue bushing. In order to avoid leakage it is important that the radii of the machine nozzle and the sprue bushing are the same.
Sprue bushings are available with no radius, a radius of 15,5 mm or 40,0 mm.
The sprue bushing needs to be fixed against rotation, if a contour giving area has been incorporated. This can be done by flattening a side or inserting a pin.
Apr 12, 2019
If the clamp force is too high for the chosen injection molding machine, multiple cavities with identical projected areas can be set behind each other inside the mold.
Despite the multiple parting plane, the clamp force is used only from one.
The reason for this is the neutralization of the cavity pressures of opposite positioned cavities.
The middle plate synchronizes by tooth gear, hydraulic or an articulated lever.
A mold that is designed in this way is called a stack mold.
Injection
Mold:
Stack mold with eight
cavities.
Related topics:
Mould Installation Height
Tiebar Spacing
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
May 10, 2019
Due to the predominate laminar flow regime in injection molding processes, primarily static mixers have the task to homogenize the melt temperature and equalizing the flow profile.
The mixing is done solely by the melt flow through flow regulating elements inside the mixer, which is placed in front of the machine nozzle.
With an optimal mixture, color inhomogeneities are eliminated leading to less needed color.
Static mixers are adapted to the injection volume of the machine. Therefore, a lowest possible pressure loss and energy input can be realized. All this can be realized with an excellent melt homogeneity independent from the through put. The product quality can be highly improved by the usage of a static mixer.
The flow regulating elements in the
static mixer lead to a homogeneous melt
temperature.
Static Mixer
Related topics:
DiagBes
This information and services are provided by:
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
Dec 2, 2021
In addition to dimensions, technical drawings often contain symbols (symbols) with values.
By this, the tolerance of important geometric properties or relationships is represented. This is used to describe permissible deviations.
The straightness tolerance specifies a maximum deviation of the contour at a certain point of a molded part.
Tolerated elements can be straight lines or axes.
The measured deviation at any point of the real component must not exceed the Tolearnz value displayed together with the symbol.
For a measuring point on a surface toleranced with straightness, it applies that this point must lie within a distance of two straight lines.
The distance between the two straight lines is determined by the specified tolerance value.
In this case, surfaces can be straight in the X-axis even though they are curved along their Y-axis.
The axis of a cylinder may deviate from its position by a specified tolerance value.
This deviation may only be cylindrical and is called ‘straightness tolerance of an axis’.
This drawing entry is regulated in the ISO 1101 standard or, for North America, in the Geometric Product Specification standard ASME Y 14.5.
Quality assurance: Example of the
tolerance specification on a cylinder axis (incl. meaning)
Related topics:
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
