Plastic Injection Moulding Machines
December 9th, 2009 | 
Author: Plastic injection moulding machines control variables in the moudling process by allowing the setter to define parameter ranges and then raising an alarm if parameters are broken. The following variables are critical to maintain:
Temperatures
Machine Barrel / Nozzle – The barrel has regional heater ‘bands’ allowing plastic to be progressively heated as it approaches the mould, reducing the chance of burning or ‘cooking’ material. Material is required to be just above its melting point as it reaches the nozzle at the end of the barrel.
Strokes, Speeds & Times
Mould Opening, Closing / Ejection / Screw Rotation, Retraction / Back Pressure – Control over the time and speed and at which parts of the machine move during the cycle can be set to precise tolerances. These values are optimised during mould trials so that production occours with moulds running at their most efficient cycles. The optimum settings for each mould can be recorded in the NC computers ROM for recall when the tool is run again.
Pressures
Injection / Follow Up / Nozzle Contact / Ejection – The pressure at which the molten plastic is injected into the mould, and the subsequent follow up pressure required to pack the plastic into the mould differ from tool to tool. The pressure required will be dictated by the amount of resistance that the mould tool puts on the flowing plastic. Design features such as hinges and narrow wall thicknesses restrict flow of plastic and so call for higher injection pressures.
The pressure at which the nozzle is applied to the back of the mould can be adjusted to prevent any material leakage as can the force with which the ejector pins push the moulding from the cavity.
Lock Adjustment
Fine adjustments can be made to the pressure holding the two halves of the mould together during the injection process. The mould must not be pushed apart at this stage as this will cause ‘flashing’ where the moulding will be useless and overblown. The pressure of the plastic can actually force the mould tool apart with extreme flashing damaging the tool. Most often when plastic flows across the mould face into mechanical parts of the tool.
Tags: Demag, Injection Moulding Machines, Plastic Injection Moulding Machines
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Manufacturing
Let S.B.Weston take care of your manufacturing requirements.
Machines
S.B.Weston Ltd is equipped with a range of electro-hydraulic Demag plastic injection moulding machines which are NC controlled allowing precise adjustments to the manufacturing process.
We have a range of machine sizes enabling us to react quickly to clients orders whilst maintaining constant production of our Weston Boxes. View our plant list for full details.
Mould Setting
Our production staff are massively experienced setting up and optimising new mould tools for production. They will work with our toolmakers to get the full potential from your mould, noting the optimum settings during mould trial for the highest quality moulding at the fastest cycletime and so gaining maximum efficiency.
The successful running and maintenance of the tool is taken care of by our setting team who will ensure the tool is monitored, cleaned, lubricated and generally serviced as it works through production.
Tags: Efficiency, Injection Moulding, Plastic Injection Moulding, Plastic Injection Moulding Machines, Production
Resources
Plastic Injection Moulding Resources
The Plastic Injection Moulding Process
If you are unsure as to exactly how the plastic injection moulding process works, and wether it is a process that will work for you and your product then read more information here.
Material Properties
There are many types of materials available for injection moulding. Read more about the properties and manufacturing potentials of the available materials here.
Plastic Injection Moulding Machinery
Plastic injection moulding machines became available after World War II when the process became popular as a way of mass producing cheap items. Read more about the evolution of the technologies involved in plastic injection moulding here.Vacuum Forming
S.B.Weston Ltd. also specialises in vacuum forming. To learn more about the process and its capabilities click here.
Tags: Plastic Injection Moulding, Plastic Injection Moulding Machines
Plant List
S.B.Weston Ltd. Plant List 2009
A brief guide to the technologies S.B.Weston ltd. has on-site at its Sunbury-on-Thames plant.
S.B.Weston Ltd. robotised its Business Card Box production in 2008. We installed a Fanuc 6-axis robot arm to remove the business card boxes from the mould, assemble the top and bottom, and pack into an outer card carton.
We run Demag machines ranging from our smallest, a D40 up to our largest, a D320. The machines are all NC III or NC IV controlled.
This 22 tonne lock BOY machine is the only non-Demag machine that we run. This machine is used for producing small components.
We have ConAir sprue pickers installed on the machines which run automatic jobs,
The sprue pickers remove the sprues from the mould face and then drop them into a granulator to be ground down and re-used.
The Hurco CNC milling machine that we have onsite is a very powerful peice of equipment. The onboard computer will translate CAD drawing files into vector paths which it can then cut into metal.
Tags: Demag, Plastic Injection Moulding Machines
Plastic Injection Moulding
S.B.Weston Ltd. Plastic Injection Moulding Specialists
Manufacturing
S.B.Weston Ltd is equipped with a range of electro-hydraulic Demag plastic injection moulding machines. Our machines are NC controlled allowing precise adjustments to the manufacturing process, necessary when moulding consistent quality products.
We have a range of machine sizes enabling us to react quickly to clients orders whilst maintaining constant production of our Weston Boxes. View our plant list for full details.
Specialist Staff
Setters – S.B.Weston Ltd. employ a team of trained machine setters who fully utilise the NC technology available on our Demag machines. Our setters are responsible for closely monitoring the performance of your mould from its initial trial right through to its final production run, making the necessary decisions and modifications to the production process to ensure that your tool runs at optimum efficiency, with the correct temperatures, speeds and pressures maintained over the production cycle.
Maintenance – We service our machines regularly to ensure their optimum performance. A team of qualified Demag technicians perform all necessary repairs and major works, whilst our setters deal with replenishing consumables such as hydraulic oils, grease and lubes.
Material Selection
Our in depth knowledge of plastics enables us to recommended a material perfectly suited to your job. Required material properties often include strength, impact resistance, flexibility or temperature resistance, all of which can be catered for. If necessary we will test run your product in a number of materials to determine which is the most suitable for the final production run.
Health & Safety
Auto-stop devices are installed on all our machines. Guarding is always present and will shut the machine down if removed or tampered with. Our staff are always trained to understand the potential dangers of the process if health & safety measures are disregarded.
We have the facilities on-site to recycle all the plastic scrap we produce and feed it straight back into our processes. All Weston Boxes are manufactured in recyclable polypropylene minimizing the effect of S.B.Weston Ltd’s environmental impact.
We deliver optimum quality mouldings across your entire production run as standard. Quality control checks will take place to ensure you get the exact spec on the mouldings you have ordered.
Machining / Assembly
We regularly perform additional machining / assembly tasks. From simple separation or assembly of multiple parts through to more complex actions such as heat insertions, printing – using hot foil techniques or jigging to set mouldings at a particular shape. We will always look to employ the most efficient methods of production, streamlining so as to minimise the amount of time and labour required and as a result, keeping the cost to you as low as possible.
Finishing / Packing
If required, we can take care of any finishing / packing that your job reqiures. We are regularly supplied packaging for injection moulded products which we assemble, pack and palletise at the time of production. This can be massively cost effective with mouldings being packed and palletised with in the machine cycle ready to go out of the door to your customers.
Tags: Injection Moulding, Injection Moulding Machines, Mouldings, Plastic Injection Moulding, Plastic Injection Moulding Machines, S.B.Weston Ltd., Weston Boxes