WO2013044375A1

WO2013044375A1 - Mold-tool system including melt-decompression-control assembly configured to selectively de-compress melt pressure in melt zone

Info

Publication number: WO2013044375A1
Application number: PCT/CA2012/050505
Authority: WO
Inventors: Heikki Sakari HYVARINEN
Original assignee: Husky Injection Molding Systems Ltd.
Priority date: 2011-09-29
Filing date: 2012-07-26
Publication date: 2013-04-04

Abstract

A mold-tool system (100), comprising: a selectively-pressurizable-and- depressurizable-melt zone (804); and a melt-decompression-control assembly (102) being configured to selectively de-compress melt pressure of a melt residing in the selectively-pressurizable-and-depressurizable-melt zone (804).

Description

MOLD-TOOL SYSTEM INCLUDING MELT-DECOMPRESSION-CONTROL ASSEMBLY CONFIGURED TO SELECTIVELY DE-COMPRESS MELT

PRESSURE IN MELT ZONE

TECHNICAL FIELD

Aspects generally relate to (and not limited to) mold-tool systems including (and not limited to) molding systems having mold-tool systems.

BACKGROUND

United States Patent number 5288225 discloses an apparatus that includes a mold cavity and a molten plastic inlet channel for communication with the mold cavity for transmission of molten plastic to the mold cavity. A valve stem is provided with substantially no net resulting forces on the valve stem due to melt pressure acting on the projecting area of its upstream and downstream faces.

United States Patent number 6348171 discloses a drool control apparatus having a piston disposed in a melt passage of a mold. The piston is moveable between a bypass position, where pressurised melt is permitted to flow past the piston to at least one nozzle, and a compression position, where the melt downstream of the piston is decompressed to inhibit drool at the nozzle.

United States Patent number 7730934 discloses a metal molding process, including passing, through a conduit passageway, a volume of molten metal located downstream of a passageway blockage formable in the conduit passageway. Also disclosed is a molded article having a body made by a metal molding process, including passing, through a conduit passageway, a volume of molten metal located downstream of a passageway blockage formable in the conduit passageway.

United States Patent Publication number 2002/0086086 discloses an apparatus for controlling the rate of flow of fluid material through a flow channel having an exit aperture leading to a mold cavity, the apparatus comprising: a pin having an axis slidably mounted in a housing containing the channel for back and forth axial movement of the pin through the channel; the pin having a bulbous protrusion along its axis, the bulbous protrusion having a smooth curvilinear surface extending between an upstream end and downstream end of the bulbous protrusion and a maximum diameter circumferential surface intermediate the upstream and downstream ends of the bulbous protrusion; the channel having an interior surface area portion which is complementary to the maximum diameter circumferential surface of the bulbous protrusion of the pin; the pin being slidable to a position within the channel such that the maximum diameter circumferential surface of the bulbous protrusion mates with the complementary interior surface portion of the channel.

SUMMARY

The inventors have researched a problem associated with known molding systems that inadvertently manufacture bad-quality molded articles or parts. More specifically, bad quality means here a poor appearance of the injection point region. Typical issues with injection point are large gate vestige or stringing.

With the current state of art hot tip hot runner systems, the most effective way to address the injection point quality issues is to decompress the hot runner in a controlled manner prior of each mold opening. Decompression is carried out by pulling the screw back. The pull back action occupies the screw for a relatively long period of time, which in turn is away from available recovery time. A reduction in recovery time is generally not desired because of many issues that come along with that. With typical beverage closure applications, the decompression function occupies approximately 40% of the otherwise available recovery time.

A valve gate style hot runner eliminates the need to decompress the hot runner prior of mold opening. However, the valve stem leaves a witness mark at the injection point. Therefore the original injection point quality issue remains.

After much study, the inventors believe they have arrived at an understanding of the problem and its solution, which are stated below.

According to one aspect, there is provided a mold-tool system (100), comprising: a selectively-pressurizable-and-depressurizable-melt zone (804); and a melt- decompression-control assembly (102) being configured to selectively de-compress melt pressure of a melt residing in the selectively-pressurizable-and-depressurizable- melt zone (804). Other aspects and features of the non-limiting embodiments will now become apparent to those skilled in the art upon review of the following detailed description of the non-limiting embodiments with the accompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

The non-limiting embodiments will be more fully appreciated by reference to the following detailed description of the non-limiting embodiments when taken in conjunction with the accompanying drawings, in which:

FIGS. 1-6 depict schematic representations of examples of a mold-tool system (100).

The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details not necessary for an understanding of the embodiments (and/or details that render other details difficult to perceive) may have been omitted.

DETAILED DESCRIPTION OF THE NON-LIMITING EMBODIMENT(S)

FIGS. 1 -6 depict schematic representations of the examples of the mold-tool system (100). It will be appreciated that the examples depicted in the FIGS, may be combined in any suitable permutation and combination. It will be appreciated that: (i) a molding system (900) may include the mold-tool system (100), (ii) a runner system (916) may include the mold-tool system (100), (iii) a nozzle assembly (810) may include the mold-tool system (100). The molding system (900), the runner system (916), the nozzle assembly (810), and the mold-tool system (100) may include components that are known to persons skilled in the art, and these known components will not be described here; these known components are described, at least in part, in the following reference books (for example): (i) "Injection Molding Handbook authored by OSSWALD/TURNG/G RAMAN N (ISBN: 3-446-21669-2), (ii) "Injection Molding Handbook authored by ROSATO AND ROSATO (ISBN: 0-412- 99381 -3), (iii) "Injection Molding Systems" 3^rd Edition authored by JOHANNABER (ISBN 3-446-1 7733-7) and/or (iv) "Runner and Gating Design Handbook authored by BEAUMONT (ISBN 1 -446-22672-9). It will be appreciated that for the purposes of this document, the phrase "includes (but is not limited to)" is equivalent to the word "comprising." The word "comprising" is a transitional phrase or word that links the preamble of a patent claim to the specific elements set forth in the claim that define what the invention itself actually is. The transitional phrase acts as a limitation on the claim, indicating whether a similar device, method, or composition infringes the patent if the accused device (etc) contains more or fewer elements than the claim in the patent. The word "comprising" is to be treated as an open transition, which is the broadest form of transition, as it does not limit the preamble to whatever elements are identified in the claim.

FIG. 1 depicts a schematic representation of an example of the molding system (900) having the mold-tool system (100). The molding system (900) may also be called an injection-molding system for example. According to the example depicted in FIG. 1 , the molding system (900) includes (and is not limited to): (i) an extruder assembly (902), (ii) a clamp assembly (904), (iii) a runner system (916), and/or (iv) a mold assembly (918). By way of example, the extruder assembly (902) is configured, to prepare, in use, a heated, flowable resin, and is also configured to inject or to move the resin from the extruder assembly (902) toward the runner system (916). The extruder assembly (902) may include (and is not limited to) a screw assembly (903). Other names for the extruder assembly (902) may include injection unit, melt- preparation assembly, etc. By way of example, the clamp assembly (904) includes (and is not limited to): (i) a stationary platen (906), (ii) a movable platen (908), (iii) a rod assembly (910), (iv) a clamping assembly (912), and/or (v) a lock assembly (914). The stationary platen (906) does not move; that is, the stationary platen (906) may be fixedly positioned relative to the ground or floor. The movable platen (908) is configured to be movable relative to the stationary platen (906). A platen-moving mechanism (not depicted but known) is connected to the movable platen (908), and the platen-moving mechanism is configured to move, in use, the movable platen (908). The rod assembly (910) extends between the movable platen (908) and the stationary platen (906). The rod assembly (910) may have, by way of example, four rod structures positioned at the corners of the respective stationary platen (906) and the movable platen (908). The rod assembly (910) is configured to guide movement of the movable platen (908) relative to the stationary platen (906). A clamping assembly (912) is connected to the rod assembly (910). The stationary platen (906) supports the position of the clamping assembly (912). The lock assembly (914) is connected to the rod assembly (910), or may alternatively be connected to the movable platen (908). The lock assembly (914) is configured to selectively lock and unlock the rod assembly (910) relative to the movable platen (908). By way of example, the runner system (916) is attached to, or is supported by, the stationary platen (906). The runner system (916) includes (and is not limited to) a mold-tool system (100). The definition of the mold-tool system (100) is as follows: a system that may be positioned and/or may be used in a platen envelope (901 ) defined by, in part, an outer perimeter of the stationary platen (906) and the movable platen (908) of the molding system (900) (as depicted in FIG. 1 ). The molding system (900) may include (and is not limited to) the mold-tool system (100). The runner system (916) is configured to receive the resin from the extruder assembly (902). By way of example, the mold assembly (918) includes (and is not limited to): (i) a mold-cavity assembly (920), and (ii) a mold-core assembly (922) that is movable relative to the mold-cavity assembly (920). The mold-core assembly (922) is attached to or supported by the movable platen (908). The mold-cavity assembly (920) is attached to or supported by the runner system (916), so that the mold-core assembly (922) faces the mold-cavity assembly (920). The runner system (916) is configured to distribute the resin from the extruder assembly (902) to the mold assembly (918).

In operation, the movable platen (908) is moved toward the stationary platen (906) so that the mold-cavity assembly (920) is closed against the mold-core assembly (922), so that the mold assembly (918) may define a mold cavity configured to receive the resin from the runner system (916). The lock assembly (914) is engaged so as to lock the position of the movable platen (908) so that the movable platen (908) no longer moves relative to the stationary platen (906). The clamping assembly (912) is then engaged to apply a clamping pressure, in use, to the rod assembly (910), so that the clamping pressure then may be transferred to the mold assembly (918). The extruder assembly (902) pushes or injects, in use, the resin to the runner system (916), which then the runner system (916) distributes the resin to the mold cavity structure defined by the mold assembly (918). Once the resin in the mold assembly (918) is solidified, the residual pressure inside the runner system (916) is released by moving the screw assembly (903) of the extruder assembly (902) in a direction away from the runner system (916). After that the clamping assembly (912) is deactivated so as to remove the clamping force from the mold assembly (918), and then the lock assembly (914) is deactivated to permit movement of the movable platen (908) away from the stationary platen (906), and then a molded article may be removed from the mold assembly (918). In parallel to the clamping assembly (912) deactivation, the extruder assembly (902) starts to prepare a new shot of melt for the next molding cycle by turning the screw assembly (903).

The definition of the mold-tool system (100) is as follows: a system that may be positioned and/or may be used in an envelope defined by the stationary platen (906) and movable platen (908) of the molding system (200), such as an injection-molding system for example.

Referring now to FIGS. 2, 3, 4, 5 and 6 (generally speaking) the mold-tool system (100) includes (and is not limited to): (i) a selectively-pressurizable-and- depressurizable-melt zone (804), and (ii) a melt-decompression-control assembly (102) being configured to selectively de-compress melt pressure of a melt residing in the selectively-pressurizable-and-depressurizable-melt zone (804). Referring specifically now to FIG. 2, a schematic representation is depicted. And in accordance with the example depicted in FIG. 2, the runner system (916) includes a melt- distribution structure (917) configured to connect an extruder assembly (902) to a mold assembly (918). The melt-distribution structure (917) may include multiple melt branches or channels for the case where the mold assembly (918) defines a plurality of mold cavities. The melt-distribution structure (917) includes (and is not limited to): (i) a melt-compression zone (800), (ii) a melt-decompression-control zone (802), (iii) the selectively-pressurizable-and-depressurizable-melt zone (804), and (iv) a plug-forming zone (806). The melt-compression zone (800) abuts the extruder assembly (902). The melt-decompression-control assembly (102) is configured to be received, at least in part, in the melt-decompression-control zone (802). The melt-decompression-control zone (802) abuts the melt-compression zone (800). The selectively-pressurizable-and- depressurizable-melt zone (804) abuts the melt-decompression-control zone (802). The plug-forming zone (806) abuts the selectively-pressurizable-and-depressurizable- melt zone (804). The plug-forming zone (806) is configured to fluidly communicate with the mold assembly (918).

Referring now to FIG. 3, a cross-section view of the mold-tool system (100) is depicted. In accordance with the example depicted in FIG. 3, the melt-decompression- control assembly (102) is included (amongst other things) in a nozzle assembly (810) of a melt-distribution structure (917) of a runner system (916). The melt-distribution structure (917) is configured to connect the extruder assembly (902) to the mold assembly (918). More specifically, the nozzle assembly (810) defines a nozzle-melt channel (812). The nozzle assembly (810) has the melt-decompression-control assembly (102). The melt-decompression-control assembly (102) is interactive with the nozzle-melt channel (812). The melt-decompression-control assembly (102) is configured to: (i) be positioned at a location that is set apart from a plug-forming zone (806) located at an outlet (814) of the nozzle assembly (810); and (ii) selectively decompress, at least in part, a residual melt pressure residing in the nozzle-melt channel (812) between the melt-decompression-control assembly (102) and the plug-forming zone (806). More specifically, the nozzle assembly (810) has, or provides, a valve seat (832), and the nozzle assembly (810) defines a nozzle-melt channel (812). In addition, a valve-stem assembly (826) is movable along the nozzle-melt channel (812). The valve-stem assembly (826) has a sealing surface (830) that is interactive with the valve seat (832). The valve seat (832) and the sealing surface (830) are each aligned and oriented along a longitudinal axis (846) extending through the valve-stem assembly (826).

The nozzle assembly (810) includes (and is not limited to): a nozzle body (816), a heater assembly (818), a tip assembly (820), a tip retainer (822), a by-pass chamber (824), a valve-stem assembly (826), a valve-stem tip (828), a sealing surface (830), a valve seat (832). The nozzle body (816) abuts a manifold system (not depicted but known) of the runner system (916) to the mold assembly (918). The heater assembly (818) is attached to an outer surface of the nozzle body (816). The tip retainer (822) attaches the tip assembly (820) to the nozzle body (816). The tip retainer (822) is attached to the nozzle body (816) as well. The nozzle-melt channel (812) is also defined through the tip assembly (820). A by-pass chamber (824) is defined by the tip assembly (820). The valve-stem assembly (826) is received in the nozzle-melt channel (812). The valve-stem assembly (826) includes a valve-stem tip (828), a sealing surface (830) and a valve seat (832).

A thermal plug (844) is formable in the outlet (814). A mold-gate insert (834) receives, at least in part, the nozzle assembly (810). A bubble zone (836) is defined, at least in part, between the mold-gate insert (834) and the tip assembly (820). The tip retainer (822) contacts the mold-gate insert (834). An air pocket (838), which act like an insulator, is defined between the mold-gate insert (834) the tip retainer (822) and the heater assembly (818). The mold assembly (918) defines a mold cavity (919). The valve-stem assembly (826) is now depicted in the no melt-flow position. FIGS. 4, 5, 6 depict the operational states of the mold-tool system (100).

The melt-distribution structure (917) includes a nozzle assembly (810) that has melt- decompression-control assembly (102). The nozzle assembly (810) defines a nozzle- melt channel (812) and also defines an outlet (814) that is in fluid communication with the nozzle-melt channel (812). The outlet (814) is also being configured for fluid communication with the mold cavity (919) of the mold assembly (918). The valve seat (832) is provided by the nozzle assembly (810). The valve seat (832) is set apart from the outlet (814). The nozzle-melt channel (812) provides the selectively-pressurizable- and-depressurizable-melt zone (804) between the valve seat (832) and the outlet (814. The valve-stem assembly (826) is configured to: (i) be received, at least in part, by the nozzle-melt channel (812) of the nozzle assembly (810), (ii) interact with the valve seat (832) of the nozzle assembly (810); (iii) be actuatably movable between a melt-flow position, a no-melt flow position, and a melt-decompression position.

Referring now to FIG. 4, a cross-section view of the mold-tool system (100) is depicted. FIG. 4 depicts the melt-flow position. In the melt-flow position, the valve-stem assembly (826) does not sealably mate with (a component of) the nozzle assembly (810), and the selectively-pressurizable-and-depressurizable-melt zone (804) experiences the approximately same melt pressure as the runner system (916) because the nozzle-melt channel (812) of the nozzle assembly (810) is in fluid communication with the runner system (916). The valve-stem assembly (826) is actuatably moved along a melt-flow direction (840) that is aligned toward the outlet (814), so that the melt-decompression-control assembly (102) permits flow of the melt from the extruder assembly (902), which is depicted in FIG. 2, toward the mold assembly (918). In the melt-flow position, the sealing surface (830) does not seal with the valve seat (832), and the melt flows through the by-pass chamber (824) toward the mold assembly (918). In accordance with FIG. 4, the selectively-pressurizable-and- depressurizable-melt zone (804) is now pressurized. As depicted in FIG. 4, during injection of the melt into the mold assembly (918), valve-stem tip (828) resides, for the most part, within the by-pass chamber (824), which enables melt flow from the runner system (916) into the mold assembly (918) past the valve-stem tip (828). In FIG. 4, the thermal plug (844) is no longer depicted because the thermal plug (844) of FIG. 3 has now been pushed into the mold cavity (919) of the mold assembly (918) as a result of the melt being made to flow into the mold assembly (918) from the nozzle assembly (810).

Referring now to FIG. 5, a cross-section view of the mold-tool system (100) is depicted. Fig. 5 depicts the no-melt flow position. In the no-melt flow position, the valve-stem assembly (826) is actuatably moved away from the outlet (814) toward the extruder assembly (902) so that the sealing surface (830) seals with the valve seat (832), and the melt no longer flows through the by-pass chamber (824) toward the mold assembly (918). In the no-melt flow position, the thermal plug (844) may now have an opportunity to form in the outlet (814). The valve-stem assembly (826) is moved along a melt-flow direction (840) that is aligned away from the outlet (814) toward the extruder assembly (902). The extruder assembly (902) is depicted in FIG. 2. In accordance with FIG. 5, the selectively-pressurizable-and-depressurizable-melt zone (804) is now de-pressurized. As depicted in FIG. 5, at the end of a hold cycle, the stem actuator (known but not depicted) that is connected to the valve-stem assembly (826) is actuated so as to move the valve-stem assembly (826) so then the valve-stem tip (828) becomes moved and resides further inside the valve seat (832), which will break (discontinue) the fluid communication between the runner system (916) and mold assembly (918). In FIG. 5, the thermal plug (844) has the opportunity to form in the outlet (814) as a result of the melt not being made to flow into the mold assembly (918). A cooling mechanism (not depicted but known) that is located proximate to the outlet (814) may be activated so as to cool down the melt in the outlet (814) and thus form the thermal plug (844) somewhat faster.

Referring now to FIG. 6, a cross-section view of the mold-tool system (100) is depicted. FIG. 6 depicts the melt-decompression position. In the melt-decompression position, the selectively-pressurizable-and-depressurizable-melt zone (804) experiences melt-decompression; that is, melt-decompression is defined as a lower melt pressure in the selectively-pressurizable-and-depressurizable-melt zone (804) in comparison to the melt pressure in the nozzle-melt channel (812) that is located in the runner system (916) (for example). The valve-stem assembly (826) is made to move further along a melt-flow direction (840) that is aligned away from the outlet (814) in order to create the melt decompression (lower melt pressure) in the selectively- pressurizable-and-depressurizable-melt zone (804). As depicted in FIG. 6, at the end of hold and prior to opening of the mold assembly (918), the stem actuator moves the valve-stem assembly (826) further away from the outlet (814) toward the extruder assembly (902), which will decompress the residual melt pressure within the nozzle- melt channel (812) located in the tip assembly (820). The clamping assembly (912) of the molding system (900) of FIG. 1 may now be deactivated so as to remove the clamping force from the mold assembly (918), and then the lock assembly (914) is deactivated to permit movement of the movable platen (908) away from the stationary platen (906), and then a molded article may be removed from the mold assembly (918). In parallel to deactivation of the clamping assembly (912), the extruder assembly (902) starts to prepare a new shot of melt for the next molding cycle by turning the screw assembly (903) for example. Prior to (or concurrent with) the injection start time, the valve-stem assembly (826) returns back to its injection position (as depicted in FIG. 4). For Fig. 6, the thermal plug (844) will, advantageously, experience less pressure (as compared to the pressure felt in FIG. 5) as a result of the decompressed melt pressure that is experienced in the selectively-pressurizable-and- depressurizable-melt zone (804), which is located in the tip assembly (820) in accordance with the depicted example. An advantage that may be realized with less melt pressure exerted on the thermal plug (844), as depicted in FIG. 6, is that the mold assembly (918) may be opened sooner than usual, and the molded article may be removed much sooner from the mold assembly (918) sooner than previously realized in the existing state of the art. The molded article will be somewhat hotter than previous, but to counteract the hooter molded article being removed form the mold assembly (918) a cooling system (known and not depicted) may be used to further cool off (in an aggressive manner) the molded article while the mold assembly (918) may be reclosed (much sooner than usual) so that additional molded articles may be made sooner. Thus the cycle time of the molding system (900) is advantageously reduced. A reduction in the molding system of just fractions of a second has a very large impact in terms of productivity of the molding system (900). It will be appreciated that the cycle time of the molding system (900) may be reduced by usage of the mold- tool system (100), which is an advantage over existing state of the art. A reduction of just a few fractions of a second provides large cost savings and/or cost reductions because more molded articles may be manufactured for a given period of time. A small reduction in pressure in the selectively-pressurizable-and-depressurizable-melt zone (804) may provide a reduction in cycle time that may be required to manufacture molded articles during operation of the molding system (900). It wil be appreciated that in FIG. 6, the melt-decompression-control assembly (102) decompresses melt pressure of the melt residing in the selectively-pressurizable-and- depressurizable-melt zone (804). In FIG. 5, the melt-decompression-control assembly (102) has not yet selectively de-compressed the melt pressure of the melt residing in the selectively-pressurizable-and-depressurizable-melt zone (804).

According to an alternative example, the melt-decompression-control assembly (102) is not positioned in the nozzle assembly (810), and more specifically the melt- decompression-control assembly (102) is included or positioned in each final melt channel branch of a manifold of the runner system (916); that is, the first portion of the manifold upstream from nozzle assembly (810). The melt-decompression-control assembly (102) is positioned upstream of the nozzle assembly (810), and outside of the nozzle assembly (810). Generally, the melt-decompression-control assembly (102) is included the runner system (916).

Technical effects and benefits of the mold-tool system (100) may include (and is not limited to): (i) hot tip style gating is desired when smallest possible injection point witness mark is desired, e.g. beverage closures; (ii) traditional hot tip style gates influence system efficiency by utilizing the melt pressure provided by injection unit for the entire duration of hold and runner-system decompression phases: (a) recovery cannot start during hold (cycle time limit if recovery limited), (b) hot runner must be decompressed by performing a pull back motion before the mold can be opened (pull-back is on the critical cycle time path - direct influence on cycle time) (c) a short available recovery time pushes the envelope for extruder unit design and or drives a need to use an oversized extruder unit; (iii) the mold-tool system (100) enables recovery during hold because hot runner and mold are no longer communicating during hold, and (iv) the mold-tool system (100) reduces the decompression time significantly because only a small volume of melt contained within the tip assembly (820) needs to be decompressed instead of the entire runner volume of the runner system (916).

Generally, the mold-tool system (100) enables breaking the communication between mold assembly (918) and the runner system (916) when desired. The mold-tool system (100) has the same injection point quality benefit that a hot tip style gates have in general over valve gate style gates. It will be appreciated that the assemblies and modules described above may be connected with each other as may be required to perform desired functions and tasks that are within the scope of persons of skill in the art to make such combinations and permutations without having to describe each and every one of them in explicit terms. There is no particular assembly, components, or software code that is superior to any of the equivalents available to the art. There is no particular mode of practicing the inventions and/or examples of the invention that is superior to others, so long as the functions may be performed. It is believed that all the crucial aspects of the invention have been provided in this document. It is understood that the scope of the present invention is limited to the scope provided by the independent claim(s), and it is also understood that the scope of the present invention is not limited to: (i) the dependent claims, (ii) the detailed description of the non-limiting embodiments, (iii) the summary, (iv) the abstract, and/or (v) description provided outside of this document (that is, outside of the instant application as filed, as prosecuted, and/or as granted). It is understood, for the purposes of this document, the phrase "includes (and is not limited to)" is equivalent to the word "comprising." It is noted that the foregoing has outlined the non-limiting embodiments (examples). The description is made for particular non-limiting embodiments (examples). It is understood that the non-limiting embodiments are merely illustrative as examples.

Claims

CLAIMS WHAT IS CLAIMED IS:

1 . A mold-tool system (100), comprising:

a selectively-pressurizable-and-depressurizable-melt zone (804); and a melt-decompression-control assembly (102) being configured to selectively de-compress melt pressure of a melt residing in the selectively-pressurizable-and- depressurizable-melt zone (804).

2. The mold-tool system (100) of claim 1 , wherein:

a runner system (916) has a melt-distribution structure (917) including the selectively-pressurizable-and-depressurizable-melt zone (804).

3. The mold-tool system (100) of claim 2, wherein:

the melt-distribution structure (917) includes a melt-decompression-control zone (802), and

the selectively-pressurizable-and-depressurizable-melt zone (804) abuts the melt-decompression-control zone (802)

4. The mold-tool system (100) of claim 3, wherein:

the melt-decompression-control assembly (102) is configured to be received, at least in part, in the melt-decompression-control zone (802).

5. The mold-tool system (100) of claim 2, wherein:

the runner system (916) has the melt-distribution structure (917) that is configured to connect an extruder assembly (902) to a mold assembly (918).

6. The mold-tool system (100) of claim 3, wherein:

the melt-distribution structure (917) includes a melt-compression zone (800) abutting an extruder assembly (902), and

the melt-decompression-control zone (802) abuts the melt-compression zone

(800).

7. The mold-tool system (100) of claim 6, wherein:

the melt-distribution structure (917) includes a plug-forming zone (806) abutting the selectively-pressurizable-and-depressurizable-melt zone (804), the plug-forming zone (806) being configured to fluidly communicate with a mold assembly (918).

8. The mold-tool system (100) of claim 1 , wherein:

a runner system (916) includes a melt-distribution structure (917) configured to connect an extruder assembly (902) to a mold assembly (918), the melt-distribution structure (917) includes:

a melt-compression zone (800) abutting the extruder assembly (902);

a melt-decompression-control zone (802), the melt-decompression-control assembly (102) is configured to be received, at least in part, in the melt- decompression-control zone (802), the melt-decompression-control zone (802) abuts the melt-compression zone (800);

the selectively-pressurizable-and-depressurizable-melt zone (804), the selectively-pressurizable-and-depressurizable-melt zone (804) abuts the melt- decompression-control zone (802); and

a plug-forming zone (806) abutting the selectively-pressurizable-and- depressurizable-melt zone (804), the plug-forming zone (806) configured to fluidly communicate with the mold assembly (918).

9. The mold-tool system (100) of claim 1 , wherein:

the melt-decompression-control assembly (102) is included in a nozzle assembly (810) of a melt-distribution structure (917) of a runner system (916), the melt-distribution structure (917) being configured to connect an extruder assembly (902) to a mold assembly (918).

10. The mold-tool system (100) of claim 1 , wherein:

the melt-decompression-control assembly (102) is positioned upstream of the nozzle assembly (810), and outside of the nozzle assembly (810),

the melt-decompression-control assembly (102) is included the runner system

(916).

1 1 . The mold-tool system (100) of claim 1 , wherein:

a runner system (916) includes a melt-distribution structure (917) configured to connect an extruder assembly (902) to a mold assembly (918), the melt-distribution structure (917) includes: a nozzle assembly (810) defining a nozzle-melt channel (812), the nozzle assembly (810) having:

the melt-decompression-control assembly (102) being interactive with the nozzle-melt channel (812), the melt-decompression-control assembly (102) being configured to:

(i) be positioned at a location that is set apart from a plug-forming zone (806) located at an outlet (814) of the nozzle assembly (810); and

(ii) selectively de-compress, at least in part, a residual melt pressure residing in the nozzle-melt channel (812) between the melt-decompression-control assembly (102) and the plug-forming zone (806).

12. The mold-tool system (100) of claim 1 , wherein:

the melt-decompression-control assembly (102) includes:

a nozzle assembly (810) having a sealing surface (830), the nozzle assembly (810) defining a nozzle-melt channel (812); and

a valve-stem assembly (826) being movable along the nozzle-melt channel (812), the valve-stem assembly (826) having a valve seat (832) being interactive with the sealing surface (830).

13. The mold-tool system (100) of claim 11 , wherein:

the valve seat (832) and the sealing surface (830) are each aligned and oriented along a longitudinal axis (846) extending through the valve-stem assembly (826).

14. The mold-tool system (100) of claim 1 , wherein:

a nozzle assembly (810) having the melt-decompression-control assembly (102), the nozzle assembly (810) defines a nozzle-melt channel (812) and also defines an outlet (814) being in fluid communication with the nozzle-melt channel (812), and also being configured for fluid communication with a mold cavity (919) of the mold assembly (918);

a valve seat (832) being provided by the nozzle assembly (810), the valve seat (832) being set apart from the outlet (814), the nozzle-melt channel (812) providing the selectively-pressurizable-and-depressurizable-melt zone (804) between the valve seat (832) and the outlet (814);

a valve-stem assembly (826) being configured to: (i) be received, at least in part, by the nozzle-melt channel (812) of the nozzle assembly (810), (ii) interact with the valve seat (832) of the nozzle assembly (810); (iii) be actuatably movable between a melt-flow position, a no-melt flow position, and a melt-decompression position,

wherein:

in the melt-flow position, the valve-stem assembly (826) does not sealably mate with the valve-stem assembly (826), and the selectively-pressurizable-and- depressurizable-melt zone (804) experiences approximately the same melt pressure as the runner system (916);

in the no-melt flow position, the valve-stem assembly (826) sealably mates with the valve-stem assembly (826); and

in the melt-decompression position, the selectively-pressurizable-and- depressurizable-melt zone (804) experiences a lower melt pressure than the runner system (916).

15. A molding system (900) having the mold-tool system (100) of any preceding claim.

16. A runner system (916) having the mold-tool system (100) of any preceding claim.

17. A nozzle assembly (810) having the mold-tool system (100) of any preceding claim.