Mailingbag.com aren’t just stockist of polythene products, we are also polythene bag and film manufacturers, meaning we are able to offer such excellent valve for money. Dealing with us directly means you are missing out the middle men, leading to rock bottom prices and a much simpler ordering process.

Our manufacturing capabilities are enormous, enabling us to design and manufacture both stock and bespoke products all at our site in the West Midlands. We are more than happy to provide you with a no-obligation quotation on any of your packaging requirement from small quantities to large quantities.

We aim to make buying polythene as easier as possible and we don’t want to baffle you with Jargon, therefore we have created a guide to polythene manufacturing to help you understand the different processes. It may also enable you to highlight the product that is best for your requirements. The guide begins explaining the different material that can be used, the extrusion process, the bag conversion process.

1 Melt Low Density Polythene (LDPE)

This film is generally used on polythene film and bags when you require a higher puncture resistance as well as shrinking capabilities. 1 Melt LDPE has no additives within the film, so it has a lower slip level making the material more suitable for stacking. During the extrusion process, the bubble can be blown in different ways, which gives the film various shrinking properties, which is ideal of pallet shrink hoods. The higher puncture resistance lends the material to being converted into heavy duty sacks.

2 Melt Low Density Polythene (LDPE)

This material is the most commonly used here at mailingbag.com as it is suitable for the majority of most film and bag requirements. Our general 2 Melt blend contains both anti-block and slip additives, which ensure the film is easy to handle and open. However we are able to add different percentages of the additives to make the film slippery or without any slip at all.

4 Melt Low Density Polythene (LDPE)

4 Melt LDPE is a very soft material that is used on the thinner gauge products such as garment covers and dust covers. This material enables film to be downgauged to reduce the quantity of film required and where the strength of the film isn’t important.

Medium and High Density Polythene (MDPE/HDPE)

This blend of material offers higher strength material when compared to normally LDPE. It can be blended with any of the above material to boost their puncture resistance. However the most common use for this blend is on thin gauges as it allows you to downgauge, however still have the same strength as the thicker material. One downside to MDPE film is that the clarity isn’t as good.

Metallocene Blends

When high clarity is important, a metallocene based product would be the best option. A metallocene blend will also give you a stronger material as well as being more resilient to cold temperatures. This blend has different properties due to the fact it is manufactured in a different way using a metallocene catalyst, however the price reflects this and is more expensive than a normal LDPE or MDPE blend.

Recycled Material Blends

Here at mailingbag.com, we reprocess all our waste and scrap material on site. This enables us to ensure we have a good quality pellet, resulting in a better quality product when compared to our competitors. The benefits of using a recycled material are it is a low cost as well as being environmentally friendly. However due to high demand and limited resources, we don’t also have recycled material available.

The Process

We start with either a virgin granule or recycled granule dependent on the material that has been ordered. The granule is mixed with other additives using a blender, which is then sucked and transported to the hopper at the back of the extruder. The granule then passed down through the hopper which feeds into a screw and barrel that has various heating zones that melts the granule.

As the granule passed through the screw it is melted and forced through the die face as a molten material. This creates a ring of polythene which is pulled up from the bottom on the machine via some nip rollers at the top of the machine. In-between the die face and the nip rollers, air is used to inflate the polythene to create a “bubble”, which dictates the size of the material.

At the nip rollers the polythene has solidified, and is folded into a layflat sheet. The layflat sheet then passes through a sequence of rollers and will pass through a corona treater if this is present on the machine. If we are doing in-line print, the material will then pass through the printer. At this point the material will be wound onto a core if the customer has ordered lay flat tubing, or we will put a knife in one side of the material to create centre-fold sheeting. If single wound sheeting has been ordered, we will put a knife in other side of the material and will then wind the material onto a cardboard core on two different back to back winders.

Machinery and Service

We currently run 7 extruders on a continually 24 hours a day production plan. The extruder vary in size allowing us to produce a range of different sizes that can be seen below. Some of the extruders are fitted with corona treaters, in-line printers and double winders for single wound sheeting. We also have the capability to print the material in up to 8 colour on our out of line flexographic printers.

We ensure with our machines that there is a cross over with the size of material they can produce, which prevents any issues if there are breakdowns or we have a busy spell. This means we are able to work to tight lead times and quick turn around.

Here at mailingbag.com we specialise in both small production runs, with very competitive prices within the industry as well as being able to cater to for high volume orders. We are able to do this due to our recent investment on all our lines being them up to date with modern technology.

Production Capabilities

Minimum Film Width: 1″ (25mm)
Maximum Film Width: 79″ (2000mm) Layflat Tube
158″ (4000mm) Centre Fold Sheeting
Minimum Film Thickness: 60 Gauge (15 Micron)
Maximum Film Thickness: 1200 Gauge (300 Micron)

Film available in Lay Flat Tubing, Centre Fold Sheeting, Single Wound Sheeting, Double Wound Sheeting and J-Fold

Machinery and Service

We currently run 12 bags machines which include 4 bottom weld machines, 7 side weld machines and a wicketting machine. However unlike the extrusion department, our bag machines only run 40 hours per week Monday to Friday. To enable us to offer quick lead times, we do hold conversion film in stock in various different width and thickness, rather than having to wait for the film to be extruded before it can be converted.

With regards to printed material, if you are able to put a covering order on, however don’t want the bags all in one delivery, we have the facility to stock hold material to be called off as and when you require. We understand that our customers don’t like to take a big delivery of bags that could last them up to 6-12 months.

With us having a range of different bags machines, it enable us to offer a large portfolio of bags i.e. bottom weld, side weld, skirt side weld, wicketted bags and mailing bags. A number of our machines have accessories such as cut out handle punches, perforations and cameras for print registration as well as adhesive glue strip applicators required for mailing bags.

Over the last few years, we have invested a lot of money into upgrading our machines so they have the latest and fastest servo motors. We have also spent money on our accessories, most recently our glue applicator, as this is the core of our business and we want to ensure we are setting the high standard of quality within the industry.

Bottom Weld Bags Production Capabilities

Minimum Bag Width: 1″ (25mm)
Maximum Bag Width: 52″ (1320mm)
Minimum Bag Length: 3″ (76mm)
Maximum Bag Length: 100″ (2540mm)
Minimum Bag Thickness: 60 Gauge (15 Micron)
Maximum Bag Thickness: 1000 Gauge (250 Micron)

Side Weld Bags Production Capabilities

Minimum Bag Width: 2.5″ (64mm)
Maximum Bag Width: 50″ (1016mm)
Minimum Bag Length: 3″ (76mm)
Maximum Bag Length: 48″ (1220mm)
Minimum Bag Thickness: 60 Gauge (15 Micron)
Maximum Bag Thickness: 600 Gauge (150 Micron)