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This article will take an in-depth look at plastic crates.
The article will bring more detail on topics such as:
Principle of Plastic Crates
Orientations and Types of Plastic Crates
Applications and Benefits of Plastic Crates
And Much More…
Chapter 1: Principle of Plastic Crates
This chapter will discuss what plastic crates are, their
manufacture, and how they function.
What is a Plastic Crate?
Plastic crates are containers used for moving or transporting
goods from point A to point B. They are also used for storage
and are made of exclusively or partially plastic material. The
basic material is plastic; it gives its distinctive character as
durability. They are more expensive than wooden or carton crates
due to their durability lasting or having a longer life span
compared to other crates.
Manufacturing Plastic Crates
Plastic crates are mostly made of high density polyethylene
(HDPE) or polypropylene (PP). Polyethylene has a higher impact
strength and a very low degradation by ultraviolet radiation,
while polypropylene has a better scratch resistance. To improve
the performance of both materials, the addition of antioxidants
and UV protectants can be made.
The type of plastic forming process used depends on the form of
the plastic crate. Each type of plastic crate has its distinct
shape and design that suits one type of fabrication process
better than the others. Below are some of the common methods for
producing plastic crates.
Injection molding is a plastic forming process that involves
injecting molten plastic raw materials into a closed chamber or
mold. This process has three main processes:
Grinding and heating the plastic until it flows under
Injecting the plastic inside the mold and allowing it to cool.
Opening the mold to eject the plastic container.
A reciprocating screw type extruder is used mainly in the
industry for plastic making for mixture; there is repeated
mixing and kneading of the screw type extruder. When the plastic
(raw materials) is ready to be injected, as the screw moves, it
pushes the plastic out of the extruder and into the mold.
To make the shape required by the customer, there is a mold
designed with specifics that contains a certain shape. Normally
it contains two parts or halves with similar features. One does
have the ability to move or it remains still while the other
part of the mold can move. After molding, the other half can
move thus to release the product from the mold in undemented
form. The mold contains several or multiple openings or
channels. These are used to introduce the plastic into the mold,
vent air, and permit some plastic to flow out of the mold.
Injection molding has restricted production when it comes to the
production of one sided containers or crates. Tubs, pails, cups,
food containers, and bowls are examples. By itself, injection
molding is not suited for producing closed, hollow products such
as plastic bottles that is why it is suited for the production
of open crates. To produce these products, an inert gas is used.
This is used because it will eliminate reactions that can incur
in the mold when the process is in motion. This is introduced
into the mold partially filled with molten plastic. This pushes
the plastic onto the surface of the mold producing a hollow
part. This process is called gas-assisted injection molding.
Blow molding is a process used for the formation of plastic
containers by inflating a softened plastic compound inside a
mold. The main steps or processes of blow molding are:
It makes use of heating the plastic and forming it into a tube
called a parison or preform.
It encloses and clamps the preform between two dies.
Inflating the preform.
Cooling and ejecting the product from the mold.
As the injection molding process occurs in a series of steps,
blow molding also makes use of the screw extruders for adding
and mixing, and heating the plastic raw materials. In the
production of the preform, the process is split into two types:
injection blow molding
extrusion blow molding
Extrusion Blow Molding
This process extrudes the shape beforehand into a hollow tube
dispersed onto one end.
Injection Blow Molding
This process, on the other hand, makes use of the production of
the shape beforehand by the injection of the plastic into a mold
with a core for air supply. Both processes (the extrusion and
injection blow molding processes) make use of air to shape the
shape beforehand against the mold.
When the two processes are compared, injection molding is
considered the best in the production of plastic crates and
extrusion molding is considered best in producing other hollow
plastic products like water jugs, bottles, storage tanks, tube
packaging as well as intermediate bulk containers.
Rotational molding, or commonly known as the "roto molding", is
a plastic casting process used in the production of hollow and
seamless plastic containers. This process does not use pressure
to form its product as does the blow molding process. Rather, it
makes use of rotations when forming the crate by spreading the
plastic melt on the inner surfaces of the mold. Its operation is
has the following steps summarized as follows:
It loads the powdered plastic resin into the mold.
It makes use of heating and melting the plastic while rotating
the mold in a certain direction.
It then cools the molded plastic.
For the final step, demolding and unloading the product is
In this process, there are different rotational molding
machines. They basically vary on the configuration and the
number of the molds and how the molds are rotated while in the
heating process. Examples of rotational molding machines are
turret, clamshell, sewing machines, and shuttle.
As a result of no high pressures involved in the process, the
molds used in the rotational molding technique are cheap. Larger
products can also be produced. Rotational molding can also be
used to form double-walled crates in the absence of any
secondary processing. Multiple products formed using the
rotational molding are agricultural and industrial storage
tanks, carboys, drums, trash bins, and insulating boxes.
Process of Thermoforming
Thermoforming is the procedure of heating thin plastic sheets to
their forming temperature and stretching them over a mold. It is
a secondary plastic forming process. It does not make use of raw
plastic resin for compounding. Instead, it makes use of a
plastic sheet or film made from preliminary steps such as
extrusion or calendaring. The processes involved in
It makes use of the heating of the plastic sheet.
It forms the plastic sheet to give its distinguished 3D shape.
Lastly there is the use of trimming the formed part from the
rest of the sheet.
There are four main types of thermoforming which are vacuum,
mechanical, pressure, and twin sheet forming. Each procedure
varies on how pressure is registered to create the thermoform.
Vacuum, pressure, and twin sheet thermoforming all make use of
the compressed air to bear down on the plastic sheet instead of
the mold. Mechanical thermoforming contains two dies that pin
against each other to disfigure the plastic.
Thermoforming is restricted to making parts with fairly thin
walls. However, the procedure is susceptible to problems that
include inconsistent thickness, warping, and webbing. It is not
quite made for the production of containers requiring rigidity.
Common thermoforming containers are the ones that are used for
pharmaceutical and food applications. They are designed for
single use. Disposable cups, trays, and clamshell containers are
The compression molding process is meant for shaping the plastic
resin by making use of pressing it against two molds. This
process is mostly chosen when producing large thermosetting
plastics products. The steps involved in compression molding are
A compounded plastic charge is placed with predefined mass
onto the lower mold.
It is compressed with plastic by lowering the upper mold with
a certain pressure.
There is curing of the plastic resin.
Lastly, there is cooling and removal of the product from the
Generally, the process of compression press is downward closing.
But another pressing known as upward closing compression is also
accessible. The mold contains internal heating elements that
soothe the plastic charge. This makes the plastic flow according
to the shape of the mold. The heat also manages to cure the
plastic. During the process of curing, some plastic may
eliminate or produce gasses that are removed through an
additional phase called degassing.
Compression molding can also be used for molding containers and
crates with fiber components. Glass or carbon fibers can be
joined while pre-forming the plastic charge.
Such as injection molding which makes use of two mold halves,
compression molding is restricted to the production of
containers and plastic crates that are open on one side.
Examples of compression molding containers that can also be
produced using this method are large bins, tubs, and trays. The
compression molding process can also be used to make plastic
caps for bottles.
Design of Plastic Crates
Designing crates can be in two configurations, the open and
closed configurations. Closed plastic crates are designed with
detachable or hinged lids, while open crates are designed
without lids and can feature a grid pattern for clear visibility
of the contents contained. There is high demand for plastic
crates from the delivery industries and food services. Most food
stuffs such as dairy products, bread, beverages, meats, seafood,
and other food items are transported in plastic food crates.
Plastic crates are often found in general storage in places such
as warehousing facilities to organize, store, and transport
goods. They are made with handles for easy lifting and handling
and are designed so that they can be stacked or nested for easy
storage and maximize storage in warehouses. There are different
shapes, sizes, and colors of the plastic materials used to make
crates. They are made to withstand different temperatures, other
loaded and stacked crate weights, and impacts.
Plastic crates are manufactured using a process called plastic
injection molding. An injection mold is a machine that uses a
raw plastic product or stock and processes it into a usable
product. The plastic injection molders start with a stock
collection in a hopper that is moved directly into a conveyance
channel. A screw will turn according to the conveyance channel,
coupled with heating, which helps to liquefy the plastic in
preparation for the mold.
A mold is a container that has a shaped cavity that, when filled
with liquefied plastic raw materials, gives the plastic its
shape when cooled. Under strict and regulated temperature
control measures, the newly molded plastic will be allowed to
cool and harden. Once hardened, the product or crate is cleansed
of imperfections if present using other processes. It is then
shipped or sent to additional processing.
Every mold can be designed in such a way that imprinting the
customer or molding company's name into the finished product is
possible; the mold needs only to be designed with projecting
letters positioned appropriately. In many cases, the stock used
or the raw material for plastic crate production is made of
High-Density Polyethylene (HDPE), which is a thermoplastic known
for its durability.
Chapter 2: Orientations and Types of Plastic Crates
The introduction of plastic crates has eliminated many problems
associated with storing goods in wooden crates and cardboard
crates. Plastic crates are accessible in varying sizes and
shapes, and each of them has its distinguished applications and
specifications. Customers or clients have the option to
determine the quality of the crate according to their usage
Plastic crates can be found in different orientations and types.
These will be discussed in this chapter.
Orientations of Plastic Crates
Plastic crates have different stacking orientations, including a
stack-nest, a stacking, or a collapsible design. The differences
are particularly important when the crate is transported empty
since the volume determines the price to be paid for transport.
Collapsible Plastic Crates
These are the most expensive crates to purchase followed by
stack-nest plastic crates and then the stacking crates.
They are designed as square and they contain rounded corners, an
efficient use of available space is possible as they can be
stacked one on top of the other. Depending on the size of the
crate, the loss of loading space compared with loose break bulk
is much better than stacking.
Although stacking crates have a rigid design, some space during
the return trip can be obtained by putting one crate inside two
others and overlapping crates during stacking. Some space gaps
in the crate's rim are needed, making transportation after
delivery also easier.
The stack-nest crates can be found with swing bars or with a
cover or be stacked at 180°.
Stack-Nest Crate With Swing Bars
The volume of the inside of a stack-nest crate is less than the
inside volume of a crate with a squared design because of its
vertically tapered shape. Effective loading space is higher
depending on the size of the crate. Five nested crates will use
up the space occupied by two stacked crates of similar size with
the swing bar design. The crates can be nested if the bars are
swung out. A swing bar is swung from the outside or from the
side over the top of the crate, forming a support for the
The stack crate is slightly stronger than the stack-nest crate
due to the bar resting on the corners, which is different in the
stack nest crate where the bar rests but on the long side of the
crate. The placement of the swing bar is made at 1 to 2 cm under
the crate’s rim therefore stacking will be easy. The placement
of the crate on top should be made within this rim. For the
fitting in of the swine bar a provision is made on the crate’s
bottom side sometimes.
Stack-Nest Crate With Cover
Besides the swing bar, two cover parts are used for the closing
of the crate, on top of which another crate can be stacked. An
advantage is that sealing this cover can prevent the pilferage
of produce. Plastic crates that consist of a cover are up to 50
percent more expensive than those with no cover.
180° Stack-Nest Crate
The box can be stacked and nested in 180 degrees turn position
by making supports at multiple places inside the box. Extra
space is required for these supports. A collapsible crate
consists of a base with sides attached to it by means of plastic
or metal hinges.
Despite that these plastic crates save space when folded and
they have an attractive design, these crates are generally not
accepted in trade, most likely due to their high purchase cost.
Types of Plastic Crates
The following are some of the most used plastic crate varieties.
Regular Plastic Crates
These are used for all kinds of basic storage conditions. They
are accessible in many various shapes, colors, and sizes. These
include plastic crates for grocery distribution. They help by
protecting fragile and delicate products such as produce. The
use of these crates brings smooth, protective handling,
excellent ventilation and good stability. In the grocery
industry, there are what are called returnable plastic crates
which are folding for inbound trips and rigid for outbound trips
used to transport all types of produce between growers and
supermarkets around the world. These plastic crates have one
common footprint and six different stack heights conforming to
the different produce and can be mixed on pallets to make the
unit loads more stable and efficient.
Ventilated Plastic Crates
These are normally used for the purpose of storage of food items
and vegetables. They are accessible in a fully ventilated and
nestable design. These include plastic crates used in the dairy
industry. They are made from a material called polythene which
is strong and resilient. There are also plastic crates that are
custom made, that can be made use of from the beginning to the
final stage of the process of handling the materials. They can
be used for farmers to the display on the shelves of the
supermarkets and then to the customer and therefore finally
Dairy plastic crates are strong to handle the process entailed
by the handling and shipping of dairy products. These plastic
crates are capable of holding automated stacking equipment,
sterilization and big temperature changes, high pressure
washing. This makes plastic crates better than wooden or
cardboard crates that are sensitive to washing, temperature
changes and cannot be incorporated into the processing line.
Closed Plastic Crates
These are high-quality closed crates that can be made in various
sizes and shapes. Generally, they are used for all types of
storage, including fish in the fishing industry and other food
items. These include plastic crates for the fishing industry.
The plastic crates are used in the transfer of the catch to the
company's holding tank, where they are processed. Seafood
processors and wholesalers mostly use these crates. These
plastic crates are better than wooden ones in the fish industry
because their handling is much easier. Plastic crates support
careful handling due to their smooth surface, unlike the nails
and splinters found in wooden crates. Their opening is also
easier as well as their closing than wooden crates that have
craftsmanship that is not accurate.
6040 Plastic Crates
These crates are designed and made for multiple purposes in 600L
and 400 W dimensions.
Jumbo Plastic Crates
These are big-sized crates which are mainly utilized in the
storage and transportation of large items.
Special Purpose Plastic Crates
These types of plastic crates are designed using special
measurements so that they can suit the application in poultry,
document storage, and toast.
Plastic Crates vs. Wooden Crates
Plastic crates can be compared and contrasted to wooden crates
in the following aspects:
Plastic Crate Safety
The handling of plastic crates is safer than that of wooden
crates because of their design, low weight, and smooth
finishing. The weight of plastic crates is significantly lower
than that of wooden crates. The back injuries associated with
the worker are reduced through the use of plastic crates
Plastic crates save space relatively to wooden crates and
because of that, they reduce the shipping and storage costs.
Plastic crates can be easily stacked on the top of each other to
save storage space.
Ease of Use
Plastic crates are uniform, have a variety of designs, and have
ease of maneuverability, therefore are easier to handle.
Plastic crates have a higher versatility than that of wooden
crates. They can be used in warm and cold conditions from -22 °C
to +60 °C without any damage, unlike wooden crates that can
easily damage by even mild temperature changes. Plastic crates
have a UV rate that is very high.
Ease of Cleaning
Plastic crates are easy to clean and therefore much more
hygienic than wooden crates. Their hygienic properties are of
importance in agriculture, pharmaceutical industries and food
industries. Plastic crates are easy to clean with steam or water
or solvents while on the other hand, wooden crates get damaged
when they come into contact with steam and water or solvents.
Leading Manufacturers and Suppliers
Chapter 3: Applications and Benefits of Plastic Crates
This chapter will discuss the applications and benefits of
Applications of Plastic Crates
The applications of plastic crates are in:
Crates in the Dairy Industry
In the dairy industry, milk crates serve an extremely important
means to supply milk cans and packets across cities and towns.
They are also important and efficient in shipping milk across
long distances, holding them firmly and avoiding spillage. While
compared to wooden and cardboard crates used in the prior years,
plastic crates have now become an increasingly gained market due
to their lightweight and resilient structures. Typically made of
polyethylene (PE), plastic milk crates are resistant to repeated
washing and ensure more hygiene in the supply process.
Plastic crates are important and play a very important role in
the agriculture industry, facilitating a hygienic and efficient
transportation process. These are suitable alternatives to the
other ones such as traditional wooden and cardboard counterparts
as plastic crates resist the growth of fungi within them. As a
result, plastic bins and crates are gaining popularity in the
market and are chosen for the transport of agricultural produce,
soil, and seeds on a large scale. Moreover, plastic crates are
also resistant to extreme weather conditions, which aids in the
secure transportation of perishable agricultural products in the
industry. The nature of the products to be transported in the
agro-industry requires extra care to be taken in terms of
hygiene and proper maintenance. Plastic allows for increased
efficiency as an element in the supply and transportation of
Fisheries utilize plastic crates and also plastic fish tubs and
ice boxes to prevent fish perishing while being transported. As
a poor conductor of heat and resistant to rain, heat, and other
harsh weather conditions, closed plastic crates protect the ice
within the crates and containers from melting and ensure that
the fish stored within remains fresh even after being
transported across long distances. Moreover, cleaning plastic
crates can also be done for the purposes of hygiene. This can be
more easily done compared to crates made from other materials.
Thus, even in case of spillage, these may be cleaned more easily
and hygienically maintained. In this industry rust is not
allowed, therefore plastic containers are more suitable when
storing and transporting fish.
Vegetables and Fruits
Transporting fruits and vegetables across long distances
requires special care and hygiene to be practiced as these are
perishable and easily affected by harsh weather conditions.
Plastic crates are popular options for transporting such goods,
because they are compact and resist external deterrents. A
variety of fruits and vegetables are transported everyday, in
plastic crates, from one place to another. In fruit and
vegetable transportation, the storage of these crates may be
done in in-built systems of pallet storage, before they are
further transported to the markets.
Grocery Stores Uses
Another major domain that utilizes plastic crates is the grocery
industry. They utilize plastic crates in the storage and
transportation of grocery items and also aid customers to carry
them easily around within supermarkets. These crates may be used
to carry packaged grocery items that need to be supplied to the
markets efficiently. The ease of transportation of even bulky
grocery items is ensured by the plastic crates’ durability and
resilience of these crates.
Benefits of Plastic Crates
They are strong, rigid crates that can be used for many
journeys, making the cost per journey relatively low.
Different sizes and shapes can be made available according to
the customer’s specifications.
The plastic crates are easy to clean and to disinfect after
Plastic crates are strong and have good weather resistance.
(This enables the crates to be used in humid areas and during
Drawbacks of Plastic Crates
Hard surface plastic crates can damage the produce (such as
tomatoes and other vegetables) and so it is advised to use
The combination of the high purchase cost and the risk of
stealing could make some types of open crates a financial
Generally, the plastic crates have to be imported.
Because of several times of use of plastic crates, the total
running cost must include the extra cost for the return trip.
Plastic crates are containers used for moving or transporting
goods from one point to the other. Plastic crates are found in a
variety of configurations including collapsible plastic crates,
stack nest plastic crates, etc. Due to their different
configurations, each plastic crate has its own unique suitable
application, for example the stack crate with cover can be
sealed, preventing pilferage of produce. Therefore it is most
suitable for use in the food industry where the food needs to be
kept clean and safe. Plastic crates also offer many advantages
such as being strong, rigid, and easy to clean. They also have
disadvantages of damaging the produce with their rough surface.
Therefore it is wise to consider the configuration and
properties of the plastic material used when opting for a
Leading Manufacturers and Suppliers
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