Home › Field notes › Padded vs Unpadded Module Panels: Protection, Bulk and Cost Compared

Modular Bag Pro · 2026-10-11 · 3,160 words · 14 min read

Padded module panels protect fragile or rigid contents from impact and from their neighbours, while unpadded panels pack flatter, weigh less and conform to whatever is put inside them; the decision is a question about the contents, not about quality. Six millimetres of closed-cell foam on all faces removes 12-18 per cent of internal volume and adds 60-140 grams; ten millimetres removes 20-28 per cent. Both constructions are developed at 500 pieces per reference, sampled over 6-10 working days, produced over 35-50 days and released against ISO 2859-1 sampling plans at AQL 2.5, with parcel transit behaviour checked against ISTA 3A. Scope is civilian contents only - instruments, electronics, tools, first-aid supplies and daily kit - and nothing here implies ballistic protection, weapon carriage or defence approval.

What padding on a module panel actually protects against

Padding does three jobs and no more. It absorbs impact energy when the module is dropped or knocked, it separates neighbouring contents so hard objects do not abrade each other, and it holds a shape so the module can be packed and closed without fighting its own fabric. It does not make a module waterproof, it does not make it crush-proof, and it does not compensate for a host body with no structure.

Impact is the job worth quantifying. A module containing a handheld meter or a compact optic needs to survive a drop of 0.5-1.0 metre onto a hard surface in the hands of a user who is tired, and the energy at 1.0 metre is roughly four times that at 0.5 metre because velocity rises with the square root of height while energy rises with height. Closed-cell foam of 5-10 mm at 30-60 kg per cubic metre handles that band; 3 mm does not, and 15 mm is wasted mass unless the contents are genuinely brittle.

Density matters as much as thickness, and the two are commonly specified wrongly. Low-density foam of 25-35 kg per cubic metre bottoms out under a drop - the foam compresses fully and the load reaches the contents anyway - while high-density foam above 70 kg per cubic metre transmits too much of the shock. The useful band is narrow, and it should be written as a range with a test rather than left to a material name.

Separation is the quiet benefit and often the real one. Two metal tools in an unpadded module will mark each other within a season of vehicle transport, and the complaint arrives as a damaged product rather than as a bag defect. A single 3 mm divider sheet prevents it at a fraction of the cost of full padding.

Spec rule: Specify padding by job - 5-10 mm of closed-cell foam at 30-60 kg per cubic metre for impact, a 3 mm divider sheet for separation alone - and pair the callout with a drop test at the height the contents will actually meet.

Volume penalty: what the foam takes out of the module

Foam consumes the space it protects. A nominal 2 litre module lined with 6 mm on every face loses 12-18 per cent of usable volume; at 10 mm the loss is 20-28 per cent. That is arithmetic rather than opinion, and it means a padded module quoted as 2 litres holds noticeably less than an unpadded one quoted at the same figure - a comparison buyers make only after the first complaint.

The honest response is to quote internal volume, not external. Measure by filling with a known medium and recording the figure, then print that number. A range that quotes internal volume across padded and unpadded modules removes the ambiguity entirely, and the measurement takes under five minutes per reference.

There is a second volume effect that matters more in use. An unpadded module collapses to 25-35 per cent of its loaded depth when empty, so a set of four empties packs flat against a panel or into a suitcase; a padded set retains its full depth and occupies the same space empty as full. For travel and everyday configurations that difference decides whether a set travels with the user at all.

Partial lining is underused. Padding the base and the two faces that meet the host body - the surfaces that take the knocks - costs roughly half the volume of full lining and delivers most of the protection, because the top face of a module rarely sees an impact.

Selection rule: Line the faces that meet the host body and the ground rather than every face, and quote internal volume after filling, so the 12-28 per cent penalty is visible to the buyer before purchase rather than after it.

Conformity and fit inside the host body or on the grid

An unpadded module conforms; a padded one resists. That is the whole of the fit question. Soft contents - clothing, food, cable coils, a rolled jacket - pack better into a panel that moulds around them, because the module then fills the available cavity completely instead of leaving voids. Rigid contents - a meter, a lens, a first-aid box - pack better into a panel that holds its shape, because the cavity then matches the object.

On an external grid the difference shows up as profile. An unpadded module on a 25 mm tape field sits 30-45 mm proud of the panel when loaded and near flat when empty; a padded one sits 60-90 mm proud whether loaded or not. On a commuter or travel body that passes through doorways, crowds and vehicle boots - or on a chest or waist carrier worn at the front - the extra 30-45 mm of standing profile is a snag and scuff source, and it is the reason many urban ranges prefer unpadded modules even for delicate contents.

Inside a host body the padded module behaves like a box in a bag: it holds its shape, it does not fill gaps, and it forces the packer to plan around it. That is an advantage in a tool or instrument layout where positions are fixed and a disadvantage in a travel layout where soft goods are expected to fill the remaining space.

Occlusion of the grid is worth checking on both. Any module covers rows, and a taller padded module covers more of them; counting usable rows with the module fitted is the only way to know, and it should be recorded on the drawing for each module in the range rather than estimated once for the smallest.

Verdict: Match the panel to the contents' rigidity - conforming panels for soft goods that must fill a cavity, shape-holding panels for rigid objects - and count the rows each module covers before the range layout is frozen.

Cost and bill-of-materials consequences

Padding adds material, parts and process steps. Material is foam sheet and a liner, typically 210D or 420D, laminated or slipped in as a sleeve. Parts are the divider sheets if specified. Process is foam cutting, lamination or sleeve insertion, and the extra sewing time that a thicker assembly costs at every seam - commonly one to two additional operations per module.

Put together, an indicative delta lands in the USD 0.60-2.20 band per module at 500 pieces, with the wide spread explained almost entirely by whether the foam is laminated to the liner in a separate pass or simply slipped in as a removable sleeve. Lamination gives better shape retention and better adhesion life; a sleeve gives easier repair and lower cost.

The last row is becoming a buying criterion rather than a footnote. A padded panel bonds two material groups together, which complicates both repair and end-of-life handling, while an unpadded shell of a single polymer family is straightforward. Where a range carries a recycled-content claim, the chain of custody is checked against the Textile Exchange standards for recycled content and the padding decision has to be documented within it.

Ask for foam, liner, labour and finishing as separate quotation lines. A single blended figure hides whether the padding is laminated or sleeved, and that single fact drives adhesion life, repairability and the end-of-life position described above.

Bottom line: Compare padded and unpadded offers on material, added operations and end-of-life separation separately, because the USD 0.60-2.20 delta is less informative than whether the foam is laminated or sleeved.

Padded versus unpadded compared across nine buying criteria

Nine criteria decide this for most ranges. Content fragility and content rigidity dominate; profile, volume retention and empty-pack depth follow; cost and process come last for most programmes, because the delta is small relative to the functional difference.

Two rows deserve expansion because they are the ones buyers get wrong in both directions. Empty depth matters far more than most range copy admits: a set of padded modules travelling empty occupies the same space as a loaded set, which is why padded sets get left behind on multi-day trips. And conformity is not a weakness of lined panels so much as a property that suits rigid contents; specifying a lined panel for clothing is a specification error, not a premium choice.

Hybrid construction resolves more cases than either extreme. A 3 mm divider at the base, 6 mm on the two faces that meet the host body and an unlined top face delivers most of the impact protection at roughly half the volume penalty, and it is the configuration most work and instrument layouts should be specified with.

Takeaway: Weigh the nine criteria against the contents' fragility and rigidity first, because profile, volume and cost rows only decide the outcome when neither fragility nor rigidity points clearly one way.

Which contents justify padding, and which do not

The contents decide, and they can be sorted quickly. Padding is justified where the contents are rigid, brittle, calibrated or expensive to replace, and where they will be carried in a vehicle, on a belt or in a bag that gets set down hard. It is not justified where the contents are soft, compressible, cheap or already protected by their own packaging.

Instruments and optics are the clearest case. A handheld meter, a laser distance measure, a compact camera body or a set of test leads with exposed connectors all benefit from 6-10 mm, and the cost of the padding is a rounding error against the cost of the contents. First-aid supplies sit in the same group, because rigid plastic cases crack and sterile packaging punctures.

Soft goods are the opposite case. Clothing, food, a rolled rain shell, cable coils and documents all pack better into an unlined panel, and padding them adds bulk without protecting anything. Spare webbing, buckles and straps are the clearest waste of padding in a typical range.

The tools row is the one most ranges get wrong. Sharp-edged tools do not need impact protection; they need separation from each other and from the shell fabric, and a 3 mm divider sheet does that at a fraction of the volume cost. Padding a tool roll is spending volume on a problem the contents do not have.

Where a range carries both classes, specify two panel types under one interface and let the buyer choose - an approach that suits compact everyday layouts as much as worksite kits. A shared attachment geometry across a padded and an unpadded variant costs nothing extra to engineer and doubles the usefulness of the range.

Judgement: Sort the contents into rigid-brittle, sharp-edged and compressible classes before specifying, because rigid-brittle contents deserve 6-10 mm, sharp-edged ones need only a 3 mm divider, and compressible ones deserve no lining at all.

Test methods and acceptance criteria for both constructions

Testing a padded module is not the same as testing the bag around it, and the distinction belongs on the order document. Three routes matter: a drop test at a declared height onto a declared surface with a declared load, a parcel transit simulation for the packed set, and a laboratory check on the foam and the shell.

The drop test is the one that predicts the field result and the one most often skipped. It needs three declared numbers - height, surface and load - because a result without them cannot be compared to anything, and a padded module that passes at 0.5 m onto carpet tells a buyer nothing about 1.0 m onto concrete.

Transit simulation covers the failure that arrives before the customer does. A set of modules packed into a master carton and shipped by parcel sees drops, vibration and compression that no single drop test reproduces, and the ISTA 3A sequence is the accepted way to reproduce it before a launch quantity is committed.

Adhesion deserves a conditioning step. Foam bonded to a liner with a water-based adhesive can delaminate after two to four years in a humid climate, and a peel check run on a fresh sample will not show it. Conditioning at elevated humidity before the peel check costs a day and prevents the complaint.

Programme terms, capacity and release inspection

Vetted partner facilities provide the capacity behind these programmes: a 4,950 m² SGS-verified floor, 137 staff, 7 production lines and 149 machines, with throughput of 200,000 units per month. Foam cutting and lamination sit with the cutting room rather than the sewing lines, so a programme specifying a laminated build should be scheduled with that cell in mind from the first week.

The development calendar runs prototype rounds of 6-10 working days, moving to 12-15 where a moulded insert or a formed shell is involved, followed by a pre-production unit and bulk over 35-50 days. Development is billed at USD 50-150 for each reference, refunded when bulk is booked; foam profile dies and screens are priced at USD 300-2,500.

Release documentation follows a fixed path. First-piece approval records foam thickness at five points, foam density, liner adhesion and internal volume by fill; in-line checks confirm that the foam has not shifted inside the shell; final random inspection follows the ISO 2859-1 level II tables, permitting nil critical faults, a major limit of 2.5 and a minor limit of 4.0. A foam sheet that has shifted into a seam allowance is a major; a minor liner wrinkle inside tolerance is a minor. Settlement is 30 per cent on order, balance before shipment, quoted FOB Xiamen at 500 pieces.

Packing and freight belong in the same plan. Unpadded modules nest and compress well; padded ones do not, so the same reference count fills a 20GP at about 28 CBM unpadded and noticeably less when every module holds its shape. Transit needs 25-35 days on the water, 5-8 days if flown, and 3-5 days by express service.

Which panel construction for which programme

Decide from the contents outward. Sort the intended contents into rigid-brittle, sharp-edged and compressible, assign 6-10 mm to the first, a 3 mm divider to the second and nothing to the third, and only then look at cost. That sequence produces the right answer in most ranges and takes under an hour.

Then check where the module will be worn. Modules that live on an external grid on a commuter or travel body should stay shallow, because 60-90 mm of standing profile snags in crowds, doorways and vehicle boots, and an unlined or partially lined panel keeps the profile at 30-45 mm. Modules that live inside a host body or on a worksite belt can be deeper without penalty.

Then decide whether the range needs one panel type or two on the same carrier platform. A shared interface across a lined and an unlined variant costs nothing extra to engineer, doubles the usefulness of the range, and lets the buyer choose per contents rather than per module - which is what most end customers actually want to do.

Finally, publish internal volume and the drop height the module was built for. Those two numbers remove most of the ambiguity a padded module generates, they cost nothing to measure, and they convert a marketing claim into a specification the buyer can check.

Closing rule for the brief: derive the lining from the contents class, keep external-grid modules shallow, offer both builds under one interface, and publish internal volume and drop height together, because those four decisions resolve the padded-versus-unpadded question without further debate.