Sandwich core guide

5052 Aluminium Honeycomb Core

5052 aluminium honeycomb core is a hexagonal cellular material made from hard-temper 5052 foil, bonded at the nodes and expanded, that gives sandwich panels very high stiffness and strength for their weight. It is the general-purpose grade for aerospace, rail, marine and industrial panels: stronger and more corrosion-resistant than 3003 core, and more economical than 5056. Densities run from about 1.6 to 12 lb/ft³ (26 – 190 kg/m³) depending on cell size and foil gauge. This guide gives the property data, explains how to select a core and lists what to specify.

By Metline Technical Team · Updated 17 October 2026

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Expanded 5052 aluminium honeycomb core block showing hexagonal cells

Foil alloy: 5052, hard temper
Cell sizes: 1/8 – 3/8 in (3.2 – 9.5 mm) and more
Density: ≈ 1.6 – 12 pcf (26 – 190 kg/m³)
Core spec: AMS-C-7438 (formerly MIL-C-7438)

Overview

What is 5052 honeycomb core and how is it made?

A honeycomb sandwich panel works like an I-beam spread over an area. Two thin, stiff facings carry bending loads as tension and compression, and the lightweight core between them holds the facings apart and carries shear. Doubling the core thickness roughly quadruples panel stiffness for only a small weight increase, which is why honeycomb panels are used wherever stiffness per kilogram matters.

Most aluminium honeycomb is made by the expansion process. Thin 5052 foil, typically 0.0007 – 0.004 in (18 – 100 µm) thick, is printed with parallel lines of adhesive, stacked sheet on sheet with the lines offset by half a pitch, and cured under heat and pressure into a solid block. Slices are cut from this block to the required core thickness, then pulled apart so the unbonded areas open into hexagonal cells. The bonded lines become the double-thickness cell walls, called nodes.

For very high densities and thick foils, the corrugation process is used instead: foil is corrugated into half-hexagons, stacked and bonded or brazed. Either way the result has clear directional properties, and knowing the directions is essential before you design with it.

Core directions

L (ribbon) direction: Parallel to the continuous foil ribbons and the double-wall nodes. Strongest and stiffest in shear.
W (transverse) direction: Perpendicular to the ribbons, the direction of expansion. Shear strength about 60 % and stiffness about 50 % of L.
T (thickness) direction: Along the cell axis. Carries flatwise compression.

Nomenclature

How 5052 core is specified: cell, foil and density

Aluminium honeycomb is described by four parameters, usually written in this order: alloy, cell size, foil gauge and density, for example 5052 – 1/4 – .0015 – 3.4. That means 5052 foil, 1/4 in cell measured across the flats of the hexagon, 0.0015 in foil, and a nominal density of 3.4 lb/ft³. Coating, perforation and whether the core is supplied expanded or unexpanded are added as separate callouts.

Parameter	What it means	Effect on performance
Cell size	Distance across the flats of a hexagonal cell (1/8, 5/32, 3/16, 1/4, 3/8 in common)	Smaller cells support thin facings better and resist face dimpling; larger cells save weight
Foil gauge	Foil thickness, typically 0.0007 – 0.004 in	Thicker foil raises density and all strengths
Density	Mass of core per unit volume, lb/ft³ (pcf) or kg/m³	The best single predictor of strength and stiffness
Thickness (T)	Slice thickness, from a few millimetres to over 500 mm	Panel stiffness rises with the square of facing separation
Coating	Corrosion-resistant conversion coating or phosphoric-acid anodise with primer	Required for most aerospace and marine work; improves bond durability
Perforation	Small holes in cell walls	Vents air and volatiles during bonding and in vacuum or space use

Density follows the ratio of foil thickness to cell size: for the same cell, doubling foil gauge roughly doubles density, and for the same foil, halving cell size roughly doubles it. Strength rises faster than density, roughly with density to the power 1.5 – 1.7 for compression, so a modest increase in density buys a significant gain in strength.

Mechanical data

5052 honeycomb core typical mechanical properties

The table lists typical values for coated 5052 hexagonal core at room temperature, as published by honeycomb producers that meet AMS-C-7438. Stabilised compression is measured with facings bonded on (ASTM C365); crush strength is the steady load during progressive crushing, used for energy absorbers; shear is measured by plate shear (ASTM C273) in each direction.

Density – cell – foil (pcf – in – in)	Stabilised compressive (psi)	Compressive at 350 °F (psi)	Crush (psi)	Shear L (psi)	Shear W (psi)	Shear modulus L (ksi)	Shear modulus W (ksi)
3.1 – 1/8 – .0007	305	200	145	215	132	32	16
4.5 – 1/8 – .0010	580	380	270	345	225	51	25
6.1 – 1/8 – .0015	1030	660	450	565	345	77	37
8.1 – 1/8 – .0020	1575	1075	760	810	540	112	50
10.0 – 1/8 – .0025	1875	1300	1070	1075	610	140	60
2.6 – 5/32 – .0007	245	150	105	170	102	24	12
3.8 – 5/32 – .0010	415	280	210	275	168	41	20
2.0 – 3/16 – .0007	180	100	70	122	71	17	9
3.1 – 3/16 – .0010	340	200	145	215	128	32	16
4.4 – 3/16 – .0015	555	375	270	335	220	50	24
5.7 – 3/16 – .0020	870	600	410	465	305	70	34
6.9 – 3/16 – .0025	1185	780	570	600	380	91	42
8.1 – 3/16 – .0030	1735	1075	760	735	490	112	50
2.3 – 1/4 – .0010	215	125	85	145	88	21	11
3.4 – 1/4 – .0015	375	235	160	235	145	35	18
4.3 – 1/4 – .0020	545	365	250	325	205	48	24
5.2 – 1/4 – .0025	770	500	330	415	270	62	31
6.0 – 1/4 – .0030	1110	650	430	535	350	75	36
7.9 – 1/4 – .0040	1505	1025	720	710	450	108	49
1.6 – 3/8 – .0010	98	70	50	88	51	13	6
2.3 – 3/8 – .0015	205	125	85	145	88	21	11
3.0 – 3/8 – .0020	315	190	135	205	128	30	15
4.2 – 3/8 – .0030	565	340	240	315	205	47	23
5.4 – 3/8 – .0040	810	540	360	435	285	66	32

The same data in SI units:

Density – cell – foil	Stabilised compressive (MPa)	Crush (MPa)	Shear L (MPa)	Shear W (MPa)	Shear modulus L (MPa)	Shear modulus W (MPa)
50 kg/m³ – 3.2 mm – 0.018 mm	2.10	1.00	1.48	0.91	221	110
72 kg/m³ – 3.2 mm – 0.025 mm	4.00	1.86	2.38	1.55	352	172
98 kg/m³ – 3.2 mm – 0.038 mm	7.10	3.10	3.90	2.38	531	255
130 kg/m³ – 3.2 mm – 0.051 mm	10.86	5.24	5.58	3.72	772	345
160 kg/m³ – 3.2 mm – 0.064 mm	12.93	7.38	7.41	4.21	965	414
42 kg/m³ – 4.0 mm – 0.018 mm	1.69	0.72	1.17	0.70	165	83
61 kg/m³ – 4.0 mm – 0.025 mm	2.86	1.45	1.90	1.16	283	138
32 kg/m³ – 4.8 mm – 0.018 mm	1.24	0.48	0.84	0.49	117	62
50 kg/m³ – 4.8 mm – 0.025 mm	2.34	1.00	1.48	0.88	221	110
70 kg/m³ – 4.8 mm – 0.038 mm	3.83	1.86	2.31	1.52	345	165
91 kg/m³ – 4.8 mm – 0.051 mm	6.00	2.83	3.21	2.10	483	234
111 kg/m³ – 4.8 mm – 0.064 mm	8.17	3.93	4.14	2.62	627	290
130 kg/m³ – 4.8 mm – 0.076 mm	11.96	5.24	5.07	3.38	772	345
37 kg/m³ – 6.4 mm – 0.025 mm	1.48	0.59	1.00	0.61	145	76
54 kg/m³ – 6.4 mm – 0.038 mm	2.59	1.10	1.62	1.00	241	124
69 kg/m³ – 6.4 mm – 0.051 mm	3.76	1.72	2.24	1.41	331	165
83 kg/m³ – 6.4 mm – 0.064 mm	5.31	2.28	2.86	1.86	427	214
96 kg/m³ – 6.4 mm – 0.076 mm	7.65	2.96	3.69	2.41	517	248
127 kg/m³ – 6.4 mm – 0.102 mm	10.38	4.96	4.90	3.10	745	338
26 kg/m³ – 9.5 mm – 0.025 mm	0.68	0.34	0.61	0.35	90	41
37 kg/m³ – 9.5 mm – 0.038 mm	1.41	0.59	1.00	0.61	145	76
48 kg/m³ – 9.5 mm – 0.051 mm	2.17	0.93	1.41	0.88	207	103
67 kg/m³ – 9.5 mm – 0.076 mm	3.90	1.65	2.17	1.41	324	159
86 kg/m³ – 9.5 mm – 0.102 mm	5.58	2.48	3.00	1.97	455	221

Typical values, not design minimums. Design allowables are normally taken as a percentage of typical (often about 75 % for minimum individual values) or from qualification testing. Densities are nominal, usually with a ±10 % tolerance.

At 350 °F (177 °C), 5052 core keeps roughly two-thirds of its room-temperature compressive and shear strength. The adhesive used at the nodes and the facing adhesive usually limit service temperature more than the foil does, so check both when panels run hot.

Supply range

Block sizes, slice thickness and tolerances

Dimension	Standard	Maximum (typical)	Typical tolerance
Ribbon length (L)	48 in (1219 mm)	about 100 in (2540 mm)	+2.0 / −0 in (+51 / −0 mm)
Transverse width (W, expanded)	96 in (2438 mm)	about 144 in (3658 mm)	+4.0 / −0 in (+102 / −0 mm)
Slice thickness (T) up to 4 in (102 mm)	any, to order	—	±0.005 in (±0.13 mm)
Slice thickness over 4 in	any, to order	blocks about 35 in (890 mm)	±0.062 in (±1.6 mm)
Density	nominal by geometry	—	±10 %
Cell size	nominal	—	±10 %

Common panel formats include 48 × 96 in, 48 × 120 in, 48 × 144 in and 60 × 120 in, and metric 1220 × 2440, 1220 × 3050 and 1524 × 3050 mm. Cores can be supplied as unexpanded block slices (very compact to ship, expanded by the user on a stretching frame), as expanded sheets, or cut to finished size and profile for direct lay-up.

Configurations

Core variants and special forms

Standard hexagonal

Regular hexagon cells, the most efficient shape for flat panels and the basis for published data.

Over-expanded

Cells stretched in W into a rectangular shape. Easier to bend around the L axis for single-curvature parts, with higher W shear and lower L shear.

Flexible-geometry core

Modified cell shapes that drape onto compound curves without anticlastic bending; used for fairings and radomes.

Reinforced (double-wall)

Extra foil layers in the L direction for local high shear, such as around inserts and hinge lines.

Perforated

Micro-perforated cell walls let air escape during autoclave or vacuum bonding and in space structures.

Microcell

Cells under about 1/16 in (1.6 mm) for very thin facings, precision parts and high-density energy absorbers.

Pre-crushed and energy-absorbing

Core with a pre-initiated crush front to avoid the peak load at the start of crushing; used in crash attenuators and landing systems.

Thick blocks and stacked core

Slices of 150 mm and more, or bonded stacks, for impact pads and large stiff platforms.

Pre-formed core

Core heat-formed or machined to a contour so it fits curved moulds without stress.

Durability

Corrosion resistance, coatings and bonding

5052 is one of the more corrosion-resistant aluminium alloys, but a honeycomb core has enormous surface area and foils only a few hundredths of a millimetre thick, so even light pitting can consume a cell wall. For this reason aerospace and marine cores use treated foil. Common options are chromate or chromate-free conversion coatings, and phosphoric-acid anodising followed by a corrosion-inhibiting primer, which also gives the most durable adhesive bond.

AMS-C-7438 sets salt-fog limits for coated core, measured as weight loss after exposure in ASTM B117 salt spray. Producers publish results well inside the limit for their coated grades. Uncoated (bare) core is acceptable for dry interior use and many industrial panels, and costs less.

Seal panel edges with closeouts, edge filler or tape so water cannot enter the cells.
Isolate aluminium core from carbon fibre facings with a glass ply or film adhesive scrim to prevent galvanic corrosion.
Avoid trapped moisture during lay-up; dry core before bonding if it has been stored in humid conditions.
Use perforated core or venting where panels see pressure or temperature cycles.

Comparison

5052 compared with 3003, 5056 and aramid honeycomb

Point	3003 aluminium	5052 aluminium	5056 aluminium	Aramid (meta-aramid paper)
Relative strength at equal density	Lowest	Baseline	Higher than 5052	Lower stiffness, good toughness
Corrosion resistance	Good	Very good	Excellent	Not applicable (non-metallic)
Aerospace specification	Commercial grades	AMS-C-7438	AMS-C-7438	Producer and programme specifications
Electrical behaviour	Conductive	Conductive	Conductive	Dielectric, radar-transparent
Thermal conductivity	High	High	High	Low (insulating)
Damage behaviour	Dents permanently	Dents permanently	Dents permanently	Recovers from minor impacts
Relative cost	Low	Medium	Higher	Higher
Typical use	Doors, partitions, signage, facades	General aerospace, rail, marine, industrial	Highest-load aerospace structures	Radomes, interiors, impact-prone parts

In short: 3003 is the economical choice for building and commercial panels; 5052 covers most structural needs; 5056 is chosen when the last increment of strength matters; aramid when radar transparency, insulation or damage tolerance is needed. See our 3003 vs 5052 comparison and aluminium vs aramid core articles for detail.

Selection guide

How to select the right 5052 core

Define the loadsPanel span, support conditions, distributed and point loads, and allowable deflection. These give required bending stiffness and core shear stress.
Set the facing and thicknessChoose facing material and thickness, then core thickness for stiffness. Remember stiffness rises with the square of facing separation.
Check core shearCompare the maximum transverse shear stress with core shear strength. Orient the L direction along the main span where possible.
Check local failure modesFace wrinkling, intra-cell dimpling (thin facings over large cells), core crushing under point loads and insert pull-out.
Choose cell size and foilPick the lowest density that passes all checks; reduce cell size if dimpling or bond area limits the design.
Add environment requirementsCoating, perforation, edge sealing, temperature and fire requirements.

Density band	Typical geometries	Typical use
Low, about 1.6 – 3.1 pcf (26 – 50 kg/m³)	3/8 – .0010, 1/4 – .0010, 3/16 – .0007	Interior panels, partitions, large lightly loaded panels
Medium, about 3.1 – 6 pcf (50 – 96 kg/m³)	1/8 – .0007, 3/16 – .0015, 1/4 – .0020	Floors, structural panels, rail and marine decks
High, over 6 pcf (over 96 kg/m³)	1/8 – .0015, 1/8 – .0020, 3/16 – .0025	Heavily loaded floors, insert zones, energy absorbers

Working with core

Cutting, forming, bonding and inserts

Cutting

Slice with a band saw or reciprocating knife; profile on CNC with ultrasonic or rotary honeycomb cutters. Holding core on a vacuum table or freezing it with a temporary filler gives clean edges.

Expansion

Unexpanded slices are stretched evenly on a frame to nominal cell size. Over-stretching changes density and properties, so check cell count per length after expansion.

Forming

Bend around the L axis, preferably with over-expanded core; compound curves need flexible-geometry core or pre-formed parts.

Bonding

Film adhesives with good fillet-forming are standard for aerospace; epoxy or polyurethane for industrial panels. Clean, dry, treated core gives the best bond.

Inserts and edges

Threaded inserts are potted into the core with a filled epoxy compound. Use higher-density or reinforced core in insert zones; close out edges with extrusions or edge fill.

Splicing

Join core pieces with expanding foam adhesive along the splice line, keeping L directions aligned.

Our article on honeycomb core joining methods discusses splicing, edge closures and their effect on panel strength.

Applications

Where 5052 honeycomb core is used

Aircraft interiors and floors: floor panels, galley and lavatory structures, overhead bins and sidewalls bonded with aluminium or glass-fibre facings.
Aircraft secondary structure: flaps, spoilers, fairings, access doors and control surfaces where weight and stiffness are critical.
Space structures: satellite equipment platforms, instrument panels and solar-array substrates, usually with perforated core.
Rail and metro: floors, doors, ceilings and partitions requiring low weight and fire performance.
Marine: bulkheads, decks and furniture on fast ferries and yachts, using coated core and sealed edges.
Industrial: machine covers, clean-room walls, optical tables, vacuum chucks and precision fixtures.
Energy absorption: crash attenuators, landing pads, drop-test fixtures and protective packaging.
Airflow: flow straighteners in wind tunnels and HVAC, and EMI-shielding vents.

Quality

Test methods and documentation

Test	Standard	What it measures
Core density	ASTM C271	Mass per unit volume
Flatwise compression (stabilised)	ASTM C365	Compressive strength and modulus of the core
Plate shear	ASTM C273	Shear strength and modulus in L and W
Node bond (tensile)	ASTM C363	Strength of the adhesive bond between foils
Flatwise tension	ASTM C297	Core-to-facing bond strength in a finished sandwich
Sandwich beam flexure	ASTM C393 / D7249	Core shear and facing strength in bending
Salt-fog corrosion	ASTM B117 (per AMS-C-7438)	Corrosion resistance of coated core

Each Metline delivery of 5052 core can be documented with density and dimensional results, foil and coating details and lot traceability, with mechanical test reports to the methods above on request.

Sources

References and standards

SAE AMS-C-7438 – Core material, aluminium, for sandwich construction
ASTM C365/C365M – Flatwise compressive properties of sandwich cores
ASTM C273/C273M – Shear properties of sandwich core materials
ASTM B117 – Operating salt spray (fog) apparatus
Plascore PAMG-XR1 5052 aluminium honeycomb data sheet

FAQ

5052 aluminium (aluminum) honeycomb core: FAQs

What does "5052 – 1/8 – .0010 – 4.5" mean?

5052 foil alloy, 1/8 in (3.2 mm) cell size across the flats, 0.0010 in (25 µm) foil, and a nominal density of 4.5 lb/ft³ (72 kg/m³). That geometry has a typical stabilised compressive strength of about 580 psi (4.0 MPa).

Is 5052 honeycomb stronger than 3003 honeycomb?

Yes. At the same cell size and foil gauge, 5052 core is stronger in compression and shear and more corrosion-resistant. 3003 is chosen mainly for cost in non-structural or architectural panels.

Which direction should the ribbon (L) run in a panel?

Along the main span or the direction of highest shear, because L shear strength is about 1.6 times and L shear stiffness about twice the W values.

Can 5052 honeycomb be supplied unexpanded?

Yes. Unexpanded slices take a fraction of the shipping volume and are expanded on a stretching frame at your plant. Expanded and cut-to-size core is also available.

Does aluminium honeycomb need a corrosion coating?

For aerospace, marine and humid service, yes: coated or anodised foil with sealed panel edges. Bare core is acceptable for dry interior and many industrial panels.

Can 5052 core be bonded to carbon fibre facings?

Yes, but isolate the aluminium from the carbon with a glass ply or scrim-supported adhesive to prevent galvanic corrosion.

What core thickness tolerance can be held?

Typically ±0.005 in (±0.13 mm) for slices up to 4 in thick and ±0.062 in (±1.6 mm) above that, with tighter tolerances possible by sanding.

Specifying 5052 honeycomb core?

Send cell size, density, thickness, sheet size, coating and quantity, or the panel requirements. We reply with a matched core and a delivered quote.

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