Containers, Totes & Trays

The question that organizes this entire category

Dozens of products, one decision underneath almost all of them: what happens to the container when it is empty?

A tote spends its life in two states. Full, when it needs to stack so you can build a stable column on a pallet or a shelf. Empty, when it becomes pure overhead, occupying floor space, occupying trailer space on the return leg, and earning nothing.

Those two states pull the design in opposite directions. A container that stacks well when full has a rim and a base that lock together, which means an empty one sits on top of another empty one and takes up exactly as much room as a full one. A container that collapses into a small stack when empty has tapered walls, which means a full one wants to telescope down into the one below it rather than sit on top.

Every product in this category is a different answer to that tension:

Answer that question first and the catalog shrinks by two thirds. Section two shows how to put a number on it.

Stack, nest, or both: the math

This decision is usually made on instinct. It should be made on your empty-to-full ratio.

How stack and nest actually works

The mechanism is simple and worth understanding, because it dictates how your people have to handle the container. A stack-and-nest tote has tapered sidewalls and an asymmetric rim. Set one on another in the same orientation and it nests down inside. Rotate it 180 degrees and the rims engage, so it stacks. One container, two behaviors, decided by which way the operator turns it.

That is also the failure mode. If your people do not turn the container, they will not get a stack, and a column of half-nested loaded totes is unstable. It is a thirty-second thing to train and it needs to actually be trained.

Nest ratio is the number to compare

Manufacturers publish a nest ratio: how many empty containers occupy the vertical space of one. A LEWISBins Polylewton SN3022-6 has a published nest ratio of 4.0:1, meaning four empties collapse into the height of one.

Where each style wins

The container types

What each one is for, and the spec that matters most on each.

Divider box containers

A shallow container with slots molded into the walls so you can drop dividers in and create compartments. This is the kitting workhorse: one container carries every component for one assembly, separated so nothing mixes and nothing gets missed.

The spec that matters is divider spacing and slot count, because that determines how finely you can subdivide. A LEWISBins DC3050 at 22.4″ × 17.4″ × 5″ is configurable on 1.25 inch centers, with 15 short vertical divider slots and 11 long ones, and carries 40 lbs. That granularity is what lets one container serve several different kits as your product mix changes, rather than being fixed at four cells forever.

Divider boxes are typically stack-only, which is the correct trade here. You want a rigid box that holds its shape so the dividers stay put.

Straight wall containers

Vertical interior walls, no taper. This gives you the maximum interior volume for a given footprint and the most usable cube on a pallet, because nothing narrows toward the bottom.

Straight wall totes are the standard for automotive and manufacturing returnable programs, and they are usually designed to a standard footprint so they cube out cleanly on a pallet. A Monoflo NSO1215-05 at 12″ × 15″ × 5″, for example, is built to the 48″ × 45″ AIAG pallet footprint, with reinforced external ribbing for stacking, a perimeter bumper, drain holes and molded label areas.

The trade is empty storage: straight wall means no nesting.

Stack and nest containers

Covered in section two. The spec to compare is nest ratio, then load rating, then whether you need vented or solid.

Vented versus solid is a real decision, not a preference. Vented walls let air and water through, which matters for wet parts, wash-line output, produce, and anything that would sweat in a sealed box. Solid walls retain small parts, keep dust out and contain liquids. Many lines offer both in the same footprint so you can mix within one system.

Stack-only fiberglass containers

Where load and heat exceed what plastic will take. Glass-reinforced thermoset composite resists bending and sagging under heavy loads, holds its shape over years so it keeps stacking and nesting correctly, and handles temperatures plastic cannot. Section four has the numbers.

Attached lid containers

A hinged lid molded onto the container, so it cannot be lost or mismatched. The right answer whenever contents travel between buildings or need to stay clean and secure.

Worth knowing: many attached lid containers nest when the lids are open, so you do not necessarily give up empty density. A Buckhorn AR24201202 at 24.0″ × 19.5″ × 12.6″ outside holds 2.3 cubic feet and 80 lbs, weighs 8.3 lbs empty, nests with lids open, and accepts zip ties, padlocks or security seals, which makes it a chain-of-custody container rather than just a box.

Cross stack tubs

Tubs designed to stack at 90 degrees to one another when full, so the tub below remains accessible, and nest when empty. Quantum's TUB series runs from 17-1/4″ × 11″ × 8″ up to 25-1/8″ × 16″ × 8-1/2″, holds up to 100 lbs, and is molded from USDA and FDA approved polypropylene with a rolled top rim, grooved bottom and six drainage holes. Matching lids are available.

Conveyor, assembly and ventilation trays

Shallow trays built to move continuously rather than sit in storage. Dimensional stability is the governing property, because a tray that warps jams a conveyor. Ventilation trays add airflow for drying, cooling and curing, which is why this format also shows up in food, pharmaceutical and cannabis drying applications.

Wire baskets

Open construction for maximum airflow, drainage and visibility. Modular stacking wire baskets and heavy duty wire baskets cover parts washing, post-wash staging, oily parts and anywhere contents need to be verified without opening anything. If a solid tote would trap moisture, this is the format.

Part wash containers and baskets

Purpose-built for the washer: drainage, chemical resistance and thermal tolerance for the wash cycle. Do not substitute a general-purpose tote here, because wash temperature and detergent chemistry are exactly the conditions that shorten a tote's life.

Materials, and the temperature trap

The single most common specification error in this category is assuming a tote handles the same temperatures a parts bin does. It does not.

HDPE: the tote default

Most totes and stack-and-nest containers are high-density polyethylene. It is tough, impact resistant, rust and corrosion proof, easy to clean, and available in FDA-approved formulations. It takes abuse and it is cost effective at volume.

Here is the trap. A LEWISBins Polylewton stack-nest container publishes a temperature range of 0°F to 120°F. A Buckhorn attached lid container publishes -20°F to 120°F. Compare that to the polypropylene small parts bins in our other guide, which are autoclavable to 250°F. These are not interchangeable numbers. An HDPE tote is not going in a hot wash cycle, an autoclave, or under hot parts, and buyers who have specified polypropylene bins for years routinely assume otherwise.

Polypropylene

Stiffer than HDPE, generally better at elevated temperature, and common on tubs and bins. Quantum's cross stack tubs are high-impact polypropylene, USDA and FDA approved. Where you need a plastic container that tolerates more heat than HDPE, polypropylene is the step up before you get into composites.

Fiberglass composite: for heat and heavy loads

Glass-reinforced thermoset is a different class of material. An MFG stack-only fiberglass container publishes an operating range of -60°F to 250°F and resists cutting oils, greases, solvents and mild acids and alkaline solutions across a pH range of 3.0 to 10.0. It will not bend or sag under heavy loads, has a smooth non-porous interior, is UV resistant, cleans with steam or detergent, and integrates with automated storage and retrieval systems.

It costs several times what a plastic tote costs. It earns that in heat treat, machining with hot chips, parts washing at temperature, foundry work, pharmaceutical sterilization and any conveyor or ASRS application where dimensional stability over years is the actual requirement.

Conductive and static-dissipative

Covered properly in section five, because there is more to it than picking the black one.

Steel wire

Maximum airflow and drainage, full visibility, and the highest temperature tolerance of anything here. Specify the finish for the environment: plain, zinc, chrome or epoxy, depending on wash chemistry and corrosion exposure.

ESD containers done properly

The counterintuitive part: more conductive is not better, and it can be actively worse.

Standard plastic is an insulator. It builds and holds a static charge, and moving sensitive components in and out of an insulative tote can generate a discharge that damages parts in ways that surface later as field failures. So you buy an ESD container. Straightforward enough.

What most buyers do not know is that you can overshoot. The damage mechanism in an electrostatic discharge event is current, not voltage. A container that is too conductive does not gently bleed charge away, it provides a low-resistance path that produces a high peak discharge current the instant a charged device touches it.

Published testing on tote materials makes the difference stark. Properly dissipative material limited discharge current to roughly 0.6 to 5.1 mA. An overly conductive material in the same test produced 100 to 132 mA with visible sparking. For context, manufacturers of highly sensitive devices have targeted a 10 mA peak current limit, and some device failure thresholds sit as low as 1 to 3 volts.

The other ESD spec: carbon content

Cheaper conductive plastics achieve conductivity with heavy carbon loading, and that carbon transfers. It leaves black residue on parts, which is a cosmetic problem on visible assemblies and a contamination problem on connectors and optical components. Quality ESD containers are formulated with low carbon content specifically to avoid this. Ask.

ESD divider boxes

The most useful ESD format for electronics assembly, because it combines static protection with compartmentalization. LEWISBins ESD divider boxes are molded in black XL conductive material, are stack-only, carry 40 lbs, and use the same 1.25 inch center divider system as the standard line. Sizes run from 10.8″ × 8.3″ through 22.4″ × 17.4″, in heights from 2.5″ to 12″.

Sizing, cube and footprint

Three measurements decide whether the order works, and two of them are not on the front of the catalog page.

Inside dimensions, and why totes have four of them

Bins have an inside and an outside. Tapered totes have four relevant numbers, because the top and the bottom are different sizes. Published figures for a LEWISBins SN3022-6 illustrate it:

• Outside top: 29.6″ × 22.4″  ·  Outside bottom: 28.3″ × 21″
• Inside top: 27.6″ × 21.4″  ·  Inside bottom: 26.1″ × 20.5″
• Height 6.1″, with 6.0″ product clearance

If you are placing a rigid item with a fixed footprint, it has to clear the inside bottom, which here is three and a half inches narrower than the outside top. Sizing off the outside dimension is the classic way to receive a pallet of totes your part will not sit flat in.

Note also product clearance, which is the usable interior height once you account for the stacking rim. It is always less than the overall height.

Footprint standardization is worth more than any single container

The value of a container fleet compounds when everything shares a footprint or a clean multiple of one. Totes that cube out on the same pallet, sit on the same conveyor, and fit the same rack bay eliminate a category of daily friction that is hard to see until it is gone.

The automotive convention is the 48″ × 45″ AIAG pallet, and containers designed to it, like the Monoflo straight wall line, tile onto that pallet without wasted edge space. If you ship to automotive, this is likely dictated to you. If you do not, pick a footprint standard anyway and stick to it.

Two load ratings, not one

Container spec sheets often publish two different weight figures and they answer different questions:

Stack height is governed by the second number, not the first. At 70 lbs per tote and 300 lbs of support, the bottom container carries about four loaded totes above it. Check both figures before designing a pallet pattern, and remember that the rating assumes an even, square stack on a level surface.

Volume, weight and the ergonomic ceiling

A container that holds 2.1 cubic feet will hold more than one person should lift if the contents are dense. The published weight capacity is a structural limit, not a handling recommendation. If operators lift these manually, size to the load a person should carry, then let the structural rating be the headroom.

Tare weight matters too, and it is easy to forget. A Buckhorn attached lid container weighs 8.3 lbs empty. On a shipment of several hundred, that is freight you are paying for on every leg.

Conveyors, washers and automation

If the container touches equipment rather than just hands, a few extra specs become mandatory.

Conveyable bottoms

A container that rides a conveyor needs a bottom designed for it. A textured or ribbed bottom tracks properly on belt and roller, where a smooth bottom can slip or hang. Published specs frequently call this out, for example the textured bottom on the Polylewton line for conveyor compatibility, and the solid textured bottom on Buckhorn attached lid containers. Check it explicitly rather than assuming.

Dimensional stability for automation

Automated storage and retrieval systems, robotic pick cells and shuttle systems all assume the container is the size the drawing says it is, every time, for years. Plastic totes creep under sustained load and warp with heat cycling. This is the strongest argument for fiberglass composite in an ASRS: it holds its dimensions, which is why MFG markets that line for automated system integration explicitly.

If you are specifying containers for automation, tell the integrator the exact model before you buy, not after.

Wash lines

Three things to confirm before a container goes near a washer:

• Temperature. Wash cycles run hot. An HDPE tote rated to 120°F is not a wash-line container. This is the most common mismatch we see.
• Drainage. Solid-bottom containers hold water, which means they come out of the washer wet inside and stay wet. Vented containers, drain holes or wire baskets solve it. Several lines include drain holes as standard, and cross stack tubs carry six.
• Chemistry. Detergents and cleaners vary widely. Fiberglass composite covers pH 3.0 to 10.0. For anything more aggressive, check the specific compound rather than assuming.

Labeling and identification

Molded label areas and card holders are worth specifying at purchase, because retrofitting adhesive labels to a tote fleet that gets washed is a losing battle. Divider boxes commonly include cardholder snaps as standard. Container ID placards give you a durable, swappable alternative for containers whose contents change.

Lids, dollies and accessories

Separate lids, matched dollies and divider sets are model-specific. Order them with the containers. A tote fleet that arrives without the dollies it was specified around sits on the floor for a month.

The returnable packaging calculation

If you are replacing corrugated, the comparison is not sticker price. It is cost per trip.

A corrugated box costs a little and is consumed once. A plastic tote costs considerably more and is consumed over many trips. Comparing the two on purchase price always favors corrugated and is always the wrong comparison. The right one:

Three factors decide whether returnables pay for you:

• Loop control. Returnables work when you control both ends. A closed loop between your own plants is ideal. Shipping to a customer who has no incentive to return the container is how fleets vanish.
• Trip count. Enough trips to amortize the purchase. Short loops with frequent cycles reach payback fastest.
• Return leg cost. This is the hidden one, and it is where nest ratio converts directly into money. Shipping back empties that nest 4:1 costs roughly a quarter of the trailer space of empties that do not nest at all.

Benefits that do not show up in a simple cost model but are real: containers protect parts better than corrugated, which reduces damage claims; they eliminate recurring corrugated purchasing and the labor of breaking down and disposing of boxes; they present better to customers; and they remove a waste stream. Weigh those alongside the arithmetic rather than instead of it.

Choosing by application

Find the row that matches your situation.

Common and costly mistakes

These come up on quote calls repeatedly. All are cheap to avoid beforehand.

Assuming a tote handles bin temperatures

The biggest one. Polypropylene small parts bins are commonly autoclavable to 250°F. HDPE totes are frequently rated 0°F or -20°F to 120°F. Different products, different resins, very different limits.

Sizing off outside dimensions

Tapered totes have four dimensions. Your part has to clear the inside bottom, which can be several inches smaller than the outside top.

Ignoring product clearance

Usable interior height is less than overall height once the stacking rim is accounted for. Published separately for a reason.

Reading only one load rating

Per-tote capacity tells you what goes in. Bottom container support tells you how high you can stack. Design pallet patterns from the second one.

Buying stack and nest, then not training the rotation

The feature only exists if operators turn the container 180 degrees. Untrained, you get unstable half-nested columns and someone concludes the totes are defective.

Treating "ESD" as a single specification

Too conductive is a real failure mode, not a theoretical one. Ask for measured surface resistance in ohms and check it against your device sensitivity.

Assuming FDA approval covers the whole product line

It is frequently color-specific. Blue and gray approved, red not, on at least one line in this category.

Mixing footprints across a fleet

Containers that do not share a footprint or a clean multiple waste pallet cube, complicate racking and slow every handling step. Pick a standard early.

Forgetting the empty leg

Return freight on non-nesting empties is a permanent cost that never appears in the purchase decision. Nest ratio is the lever.

Ordering containers without dividers, lids or dollies

All are model-specific. Adding them later means a second freight bill and a gap in between.

Cleaning and service life

Containers in a returnable loop are cleaned constantly. A few habits protect the investment.

• Wash within the temperature rating. The most common cause of premature tote failure is repeated washing above the rated temperature. Warping starts subtle and ends with containers that no longer stack or nest correctly.
• Match chemistry to material. HDPE and polypropylene handle standard detergents well. Fiberglass composite covers pH 3.0 to 10.0 and cleans with steam or detergent. For aggressive specialty cleaners, check the specific compound.
• Drain fully. Solid-bottom containers hold water in the corners. Invert to dry, or specify drain holes and vented walls if wet containers are slowing you down.
• Do not exceed load ratings, even briefly. Plastic creeps. A container held over its rating deforms permanently even without cracking, and a deformed rim compromises the whole stack above it.
• Stack square and on level ground. Ratings assume an even vertical load. An offset or leaning stack concentrates force on one corner.
• Inspect rims and bases on a cycle. The stacking rim and the base are where fatigue shows first. Stress whitening and hairline cracking are the early warning.
• Keep colored containers out of prolonged UV. Sunlight through a dock door or skylight fades and eventually embrittles pigmented plastic. Fiberglass composite is UV resistant.
• Retire rather than repair. A cracked container in a stack is a hazard to everything above it. Pull it.
• Standardize on a few models. A small number of models across the facility means damaged containers get replaced from stock immediately rather than waiting on a purchase order.

Frequently asked questions

What comes up most often on quote calls.

Quick-reference spec table

Published manufacturer figures for products referenced in this guide. Confirm the exact model before ordering; specs vary within every line.